Well, for starters, they objectively have more outreach than non-JP players. And some of them are extremely vocal on JP social media, posting stuff that is apparently
not always nice. (this is from a documentary aired in Japan, it talks about FFXVI release, but the same reportedly happens for FFXIV as well).
Now, about the raiders in particular, let's do a little thought experiment: imagine that you have to do some kind of additional activity besides MSQ to unlock savage. An attunement quest, a gearing-up effort that involves more than crafting a 710 set and run normal for 710 blue gear, some reputations to unlock etc. That kind of measures would not be popular with some raiders, because for them, it would take time from raiding to do these "chores". How would they react? Well, essentially, see above.
These people love raiding (and there is nothing wrong with that), but the thing is, the raids are developed at the expense of other types of content. And that's where the twist comes: since JP players run Savage much more than EU/NA players, SE sees no qualms about persisting in this logic. The problem is that they turn off a lot of players in EU/NA in the process.