Speaking as someone who came back with the Welcome Back Campaign and the promise of Legacy as well as someone who experienced the Alpha/Beta game...I'd say the leveling is just fine. It's long enough for a new player to get oriented (Assuming they don't just PL) and short enough that people who've already climbed to 50 a couple times won't loose their minds doing it again.

I made 50 in two weeks playing about 6 hours a day because I played before. I think people need to step back and realize two things:
  • Making a ridiculous grind is gonna alienate some newbies which is something this game does not need. It was bad enough fresh starting in FFXI eight years ago.
  • This is lvl 50, traditional cap is lvl 99 or 100. There's gonna be plenty of grind POST 50 for everyone.

PS: I didn't have time to look through 15 pages of whining and this is strictly from my perspective.