This might have been brought up here before and if so, I apologize. I didn't see any recent threads about it when scrolling through.
Something I always experience when I go through the early game again on alts is the jarring sudden shift in voice acting. The English-language voice actors have all been consistent since 3.0 (minus Yugiri, obviously, for tragic reasons), which is great, but going back and replaying old content and hearing completely different voices coming from the characters' mouths is always a little uncomfortable. I remember it being pretty distracting the first time I went into Heavensward, too, even though I did vastly prefer the new cast's performances.
I don't mean to disrespect the 2.0 voice actors at all, as I'm sure they did the best they could with what they were given to work with, and some of the performances really did stand out. I absolutely adore Sam Riegel's performance as Alphinaud, for example, even if he can't really keep his accent consistent. The sheer amount of sass in his line deliveries is just perfect.
The lack of consistency between expansions is unfortunate, though, and kind of takes away from the experience. For example, with Papalymo's voice being so drastically different between 2.x and 3.x, the player doesn't even realize that it's Papalymo narrating some certain scenes near the end of the story. This isn't an issue for players who use Japanese audio, since they'd recognize the voice immediately as Papalymo's, but for somebody playing with English voices, it's very unclear who's actually voicing those lines until you finally run into Papalymo in person later and he has that same voice.
I think the best way to rectify these issues would be to go back and redub the 2.x content with the current voice cast. The two best arguments against this would be cost (which I don't think would honestly be that huge of a hurdle for a company like SE, and it's not like all that many scenes from 2.x were fully voiced anyway), and potential perception of disrespect to the old voice cast. But I really do feel like having a sense of consistency between the different expansions is pretty important in such a story-focused game, and I doubt the old voice cast would take it too personally.
So, is there any chance of this ever happening? I don't think it's ever been brought up in any interviews before, but I might have missed something.