Basch was the main character of FF12 until some higher up decided that they needed an "audience avatar" for the people playing the game to relate to. Vaan and Penelo were inserted "last second". If you need any proof of that, look at how little they affect the plot or even cutscenes. They're there because someone decided the main characters weren't good enough for being "audience avatars" for the players.
Tidus exists to be an "Audience Avatar" as well. These are very common writing devices (I love to write, so yes, knowing these things is part of the job) that are used to get your audience up to speed on the strange world they've just been dumped into. Lots of games have these things (though some are executed better). Look at Final Fantasy 6. Terra is our "Audience Avatar" as she's given absolute amnesia and slowly fills in the blanks as the player learns more about the world they've been put into. Things everyone in the game knows are explained to her up until she turns into an Esper. At that point, another Esper fills in the blanks for us and explains what Terra is and what is going on, so Terra ceases to be the "Audience Avatar", as you're now up to speed on what the world you're playing in is about. Let's look at Final Fantasy 7. Cloud is our "Audience Avatar" in that. People start off explaining to him what AVALANCHE is and why they're doing terrorist jobs. They explain about the Shinra corporation and the town in general. These are things that Cloud should actually know before starting the game, but they're explained to him because he's "just a mercenary" and has "no stake in the politics". Other people even explain to Cloud what SOLDIER is, despite the fact that he was a member of it and should know what it is. These are meant to catch up the audience to the plot.
In fact, anytime you have a plot where you play as a character with "amnesia" of any kind, that's pretty much the case. You're playing as an Audience Avatar. Someone who is there to just have the world and events explained to them, even though they would know those things if they didn't have amnesia.
Or, almost anytime you have a "fish out of water" storyline, the character who is the "fish out of water" is also the "Audience Avatar", as they are the ones exposition is most spouted to in order for them to learn things (and for the audience to learn things too!).
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It doesn't matter why she wanted Tidus or Rikku to join. The Point I was making was that she asked them to join despite the protests of her Guardians, which means that she isn't "a pushover to everyone". It was used as an example of the inconsistency of that character trait. You're just adding more proof to that point (by basically pointing out she's making these decisions herself and for her own reasons, despite the reasons her guardians give her for not doing those things).
If it was her hometown, they wouldn't say "A summoner has been in the temple for X days". They would say "Yuna hasn't come out of the temple yet, should we worry?". Words mean things, and the way the villagers word it is very important. They don't say who it is, only that they think she's in trouble. They don't even hint that she's famous. They don't even say that her father was famous. You'd think in their hometown, they'd mention stuff like that, as it would be a point of pride for the hometown. The point remains, she didn't become a Summoner because other people told her that's what she had to be. She decided to become it on her own.
We do see that the rest of the world treats her as a rockstar, yes. However, it's not something she's used to when we first see it. The look on her face and her initial reactions to these fawning people is often one of confusion. You know, as if she's never had to deal with it before. She decides fairly early on that the best way to deal with these people is simply to smile, laugh, and offer help if she can. She decides that it's her job to try to give people hope and joy and maybe 10 more years if she can manage it (now compare this to the other Summoners we run across who also have similar rockstar statuses amongst the populace and don't decide to take her route of dealing with it).
The luggage she packed is meant to be endearing, actually. "These are gifts for all the shrines we are going to visit" she says. She had packed special things to give to the shrines she was going to pray at. Lulu has to tell her that not only is it too much to be lugging around, but that the shrines/temples don't actually care if a Summoner brings gifts or not. The scene is painted as "her heart is in the right place, but she's naïve". Because of that, it's painted more as "endearing" than as "character flaw".
I don't actually remember the "being nice to the little girl on the road" part. However, I do remember her being nice to practically everyone you ran across, including people who were rude and mean to her (and with nobody knowing they were rude to her, so she didn't actually have to be nice!). On top of that, Yuna doesn't actually question everything until the fight with Yunalesca. Up until that point, she believed in the Summoner's Path despite how terrible the teachings of Yevon actually were and how corrupt the people running it were. She simply thought the people running it were "corrupt" and not that the teachings actually were. But, once we get through the fight with Yunalesca, the game is basically over anyway. All that's really left is simply fighting Sin. So, it takes her the whole game to figure out and decide (with Tidus's prompting, no less!) that the Summoning Way was all wrong and didn't need to go down that way.
Now, I get that people would think "she puts on a fake smile, but she's really depressed, so it's a character flaw". Sure, makes sense. The problem is, however, that it never interferes with the character, or the story, or any of the relationships in the story. In fact, it's treated endearingly and is the entire thing that allows her and Tidus to bond and fall in love. It's not so much a "flaw" as it's a vehicle for starting a relationship between the two lead characters. In fact, after the forced laughing scene, it's never brought up again that she's "fake smiling". No, not even from Tidus.
I just say that she's a huge Mary Sue and it drives me crazy. It drives me crazy because it didn't need to happen in terms of writing and execution. They could have inserted situations in which her Naïve nature actually caused real problems for the group (which it never really does, as even her stupid plans really wouldn't have any negative consequences for her, the group, or even Spira). Maybe if it had been her to suggest fighting the "Chocobo Eater" instead of Tidus, it could've been a good "flaw" to show off. Maybe if she had put the group in real peril through her naïve way of thinking, she wouldn't be so much of a Mary Sue. Maybe if her need to be "babysat" put the group in real danger or caused real public political backlash, it could've made her less of a Mary Sue. Instead, we get the most perfect of characters imaginable whose only flaws are played as "endearing qualities" instead of actual hindrances or things that need to be worked out (you know, like Rikku's fear of Lightning and Thunder? Or maybe Kimahri's old grudges and feeling not as good as his tribe? Or maybe Wakka's Fantastic Racism towards Al Bhed? Maybe Lulu's distrust of outsiders as well as her emotional barricade?). Yuna just... has no problems. She has nothing to work out. She has no qualities that need to be fixed (as they actually aren't problems at all in terms of the storyline or even character relationships). She's just the closest to a Jesus Allegory Square Enix ever gets with a Final Fantasy character.
To someone who writes stories and creates characters... Yuna is a very frustrating character to behold as she could've been done properly and could have avoided all the Mary Sue stuff without issue. It's so obvious that it was a conscious decision by their writing staff to make her intentionally into a Mary Sue.
