No, they're not ruining the game, they're fixing things in the game. Seriously, if you can't handle a couple hours of downtime here and there...

Also, midnight is generally considered the end of prime time. Besides that, it's midnight pacific, which means the majority of the US is already well past prime time.

Anyway, as others have noted, FFXI often went weeks or even months with no downtime (though there was usually lots of downtime in the short term after new version updates). Such will likely be the case here once the game has matured more.