You have a game that is designed for weebs, by weebs. It's a game with permanent character death and this makes it so that you really grow attached to your party members, lest you permanently lose them. On top of this, it's in an RPG whose world, as a whole, is rather grimdark, with helps foster the character relations quite a bit. You genuinely grow to feel for these characters, so any sort of editing will be picked up on immediately. Some level of alteration's fine in an adaptation - a great example of this is Frog in Chrono Trigger - he speaks Olde English in the localized version, a new quirk - but his lines are otherwise completely unchanged and his personality and dialogue is surprisingly not changed much.
This
is not what happened with the characters in
Fire Emblem: Fates. Instead, major things like character motivations were changed, major individual character arcs being flat-out removed for no particular reason, and several characters were flat-out flanderized. A character who liked pickles as a quirk is now
sperging about them harder than CWC. Characters with a touching discussion moment now have shit replaced with a string of "........" statements. These dialogue and gameplay changes are done in a way that is more than simple meme-age; the changes are done in such a way that it completely destroys not only immersion, but when it outright fucks with story or gameplay elements. The stupid memes and bad dialogue further just make the work look dated.
Sometimes the changes completely destroy existing precedents as well. A really good example is the male version of Kana; in the localized version, 90% of his finalized S-rank supports end up with him either flat-out rejected or "just friends," which makes it so that the best combat bonuses he can get are tied to a character who he is not romantically linked to, and, in the way the game universe of FE works, cannot ever assign to someone who will (you're only allowed one S-Rank in your entire life, and it's supposed to be to who you marry). In the Japanese version, there is no Rejection segment; Kana winds up married in all of them, and in over half of them, the female character proposes to
him.
According to the weebs, over 60% of the game's dialogue was also axed. Yeah, there's pervy content axed too, but for the most part the overpowering majority of it was butchered for the sake of butchering it. The changes are too big and too sweeping to ignore for the sake of gameplay; you can scarcely go far without finding some new area the translation botched, removed content, or so on. A lot of this shit seems increasingly have been done to push an agenda, making it that much worse.