I believe that I'm too much of a hardcore player to use a dungeon skip feature.
It's a useful feature for speedrunners and testing purposes, and I think no one will be bothered by it as long as the switches are invisible. Nevertheless, the feature is much less useful when - like in the beach area that connects Sandfall Village and Gruth - both hidden skip dungeon switches can only be used once. On the other hand, there probably isn't any need to use them more than once.
Since Gianmher mentioned the invisible bridges in said area: Taking the path to the NPC wearing a blue cap gets the player permanently stuck. If the player reaches the tile directly above this NPC, he won't be able to get back. By the way, this area even contains a "new" treasure chest (holding only an Adventure Cap, though).
Sandfall Waterway has a story of its own: The player can later (before acquiring the airship for the first time) return to the Sandfall Waterway and even jump down the waterfall. When doing this, Eddy's conversation with Det is triggered once again, even if Det has already left the party. Fortunately, jumping down the waterfall again doesn't seem to mess up story progression. After reacquiring the airship subsequent to the Black Tower events, though, this issue can be game-breaking. Landing the airship in the secluded mountain area between both parts of Sandfall Waterway and then jumping down the waterfall means that the airship is permanently lost (because the southern entrance of Sandfall Waterway is blocked), and without the airship the player can't finish the game. Thus, the waterfall jump should be one-time-only and disabled after that.
Tayra is plagued by two game-breaking bugs:
When triggering the throne room cutscene: Being able to move can get the player stuck if he walks upwards and blocks the door while the Chancellor tries to exit the palace.
Tayra: The player can attempt to trigger the throne room cutscene again (which shouldn't be possible), only this time the game freezes: The soldier can't go inside, because he's blocked by the Chancellor, who already stands behind him. I don't know if or how this is related, but I probably didn't do me a favor by clearing the Tomb of the High Kings before conquering Black Tower. Well, I got the bow (Det being the last man standing after the boss's final holy counter), so I did me favor after all.
These issues are all potentially game-breaking, but let's be honest: The player has to aim at most of them in order to trigger them.
I'm still having a blast, so I'll continue my playthrough now.
