1) Prime time issue.
> Most of MMOs on this planet works with localized servers and players do not complaint about this. Non-issue. Only issue if you have either an activity with a "non standard" schedule (working during the night etc.), or no activity at all and plays 16 hours a day. I work 9 to 6, I don't care about finding people online at 3am, just like many players in here. The life around you is organized around this. Why does school starts at ~8am and ends at ~6pm? Same for work. Same for everything. Do you watch the news at 3am? Do you watch sports (in your country) at 3am? Nope. Why would I play a MMO at 3am? Some may want to, but that's a minority, a global policy shouldn't be based on a minority.
2) Wipes
> No one ever said that speaking the same language prevents wiping. It does helps however to reduce misunderstanding and thus wiping.
3) Respect
> Doesn't matter where you go, you'll always find stupid people could they be JP, NA or EU. But when they speak JP (or French/German) and you don't understand them, obviously, you can't tell if you are being treated with respect or not.
Actually in XI, I remember not even being treated at all when I was in JP parties (day time in Europe/JP prime). Everyone was speaking JP, I would just listen to music and ignore the chat. Best social interaction ever. Using pre-constructed sentences. My cat expresses more feeling than a JP player just saying {Hello !}, {Congratulations !} every time someone levels up and {See you again!} when party disband.
(And don't get me wrong on this, I was in a LS with JP players, and some were trying to speak English and we were getting along fine, but in general, the language barrier would simply prevent social interaction. Auto-translate != social interaction.)
4) EU languages + time
> "16 languages" is a complete over statement, English/German/French will be dominant outside Guilds that specialize in a specific language. There are chances that you end up in a party where everyone speaks Russian, Italian or Novergian, but that will be very rare, unless you are in a group with players from the same Linkshells.