You're preaching to the choir, buddy, but no, that's not just my opinion. That's basic game design principles. One person is an opinion; I'm talking about what hundreds of thousands of players have noticed.
I'll be happy to tell you about the many things wrong with FFXI, but GW2 is a game that genuinely had potential that was wasted for the reasons given. The problem with your argument is that you don't really know anything about GW2, so you don't really know what you're arguing.
I've not played gw2, if you can make it to level cap within a month, maybe there's a problem with the game. If you can make level cap in 2-3 months of moderate playing, I see no real issue with that, assuming that there's some sort small grind, or tiered endgame content before you can tackle the hardest enemies in the game. While in XI, to be really good at what you were doing, you needed to go back and level support jobs, you had to wait for group invites and also unlock the next set of levels. It was literally impossible to play the game at your own pace.
In GW2, you can make it to the level cap after 2 months of relatively casual play, and then there is almost nothing else to do. There are things you can do to improve your character, sure, but there's no reason to do them, because your character has already done everything there is to do. You can get a better weapon, but what will you use it against?
This might be nitpicky, and would probably boil down to a personal preference, but you're much more likely to see incremental upgrades in ARR, similar to other games. Gear in XI played a much more crucial role than it did in other games, if only because entire sets of gear were required to perform certain functions. If you were a tank who couldn't hit the gear haste cap, you were automatically more of a liability, since you'd be less likely to always have shadows up. Also, it wasn't uncommon to have a piece of gear 20-50 levels lower than your current level. Other games aren't like that; gear will always make a difference, but not in the same way that it did in XI.
GW2 put virtually no thought into its gear whatsoever. There are almost no special effects, and the equipment is generic as it could possibly be. The best weapons in the game don't even do anything special... just damage and a couple of stat bonuses. A level 80 staff frequently looks the same as a level 1 staff. And gear doesn't even drop off of specific monsters. You don't have to kill the epic dragon of doom to get anything... all monsters drop generic equipment... which can all be easily purchased on the Auction House (with real money, no less).
While I initially enjoyed the class system in XI, I really only played one or two classes. I was also really bummed out when I had to go back and level sub jobs that I had no interest in. This aspect of the game could possibly be a turn off to potential players who have interest in just one class or role. Another issue that arises is that developers can get lazy with class balance. We saw this all the time in XI, Paladin and Ninja constantly flip-flopped as to which was the better tank. If you have players who are locked into a single class, devs can't brush them off and say "Well, this encounter isn't really designed for that class."
GW2 doesn't use a subjob system, and no one is suggesting that it should. However, when you cap out your character in GW2, you're basically done with it. Might as well delete it and start a new one...really. I liked my character and wanted to keep playing on it, and I wanted to level new classes, but there was just nothing for me to do. And class balance is a moot point in GW2--it's not good. Allowing class changes wouldn't make it worse.
If you haven't played GW2, you can't take what little you've learned about it here and transplant that to what you know about FFXI. They're -completely- different games. Besides which, no feature is good or bad without regard to the system it operates within. That said, all games operate within the system of the player psychology, which is relatively static and does follow certain rules. So while a certain feature or trait of a game can be subjectively good or bad based on a player's opinion, if attempting to make a financially successful game that appeals to a wide audience, there are absolutely features that are objectively good or bad with respect to the players who engage with the system. If 10,000,000 players engage with your system, then it is good. If a new feature reduces the number of players, then that new feature is bad, and has made your system objectively worse.