Yeah, it's up to the dev. My first RPG VX ACE game, everything you could mess with and get some message. Most found it neat, and they wanted to touch everything. It breaks down precisely, as SGHarlekin said. You expect it it's fantastic unless it petters off, then you feel things for no reason, and it's sad or annoying. I wouldn't say I like that, don't click everything; boom, fixed.
Then you got the hidden rare things some people like it, but it makes you want to touch more, less happy noises as he put it its neat when you find something, but you don't wish to handle everything after a while and stop trying way sooner than when stuff has some message.
Some players, you do it well enough, end up with an extra 10 minutes to an hour of playtime. Others will touch things that might contain something, whether from experience in that game or others. Like, I played some checking pantry shelves, and bookcases sometimes get you things, but honestly, if you don't get any message, it gets old, and you check cupboards, and unless you find something first, like 5 mins of the game doing that I don't check them ever again.
Then you got the sparkles or other things to lure the player, these are nice, especially if it is a quest related, and they made it too hard to find for casual with it. But also make it, so you never check anything that doesn't sparkle and make a b-line to them every time. Like, I am tempted to use sparkles more as a joke. Do a trap with them, Have something in the intro with it, and you run to it, and it sets off a cutscene for a surprise, lol. But if you do that, they expect the next one to be a trap or lead to something more unique than usual.
To me, the only time it gets too tedious as a gamer is when you find out you have to check everything, even with sparkles, see some go overboard, and it's like, "oh, I probably need one of those 3 in that maze for the story, damn it I got pick all three you did this on purpose!" But I classify those same as those puzzle games where one is ok, but they do like 5 push the mini boulder games, like, "no, no, one was too many, but I will take it. You want me to do five. This is just filler!"
In my final opinion on this, Easter eggs are lovely; sparkles are good if it's essential; that would be hard to find without them for a quest or the story. But shouldn't everything that might have something or it might be something suitable or be a waste of time. I've seen games do that it's. It's "oh, a quest item I needed, nice! Oh, this one has a joke message, now; now to rethink how bad I want to reach each of these sparkles when I see them..."