Didn't read any of the however many pages of responses, so (hopefully) most of what I am about to say has already been said.
So, first off lets point out that actually one of the main reasons ffxiv lost a lot of its first day players was because exp was initially excruciatingly slow (fatigue says hi), NOT because it is fast now. The exact opposite of what you say.
1. Wrong, just wrong. The in-game economy is incredibly healthy considering the abundance of gil hoarders with almost capped gil, constant patches completely changing stat magnitudes (1.20?) and dependances, making all kinds of gear useless. "Useless" gear exists in all MMOs, and it doesn't affect the economy at all because it barely interacts with it! Just look at the vast amounts of dated, relatively useless gear in any mature MMO, clearly not an economy killer.
2. I know people that took a job to 50 in a week and play it perfectly, i also know people that took a job to 50 over the course of a year and suck at it. You have all the time in the world to learn a job when it's 50, and you can't even begin to master it until it is, if you think you are good at a job just because you took a long time to get it to 50, you are sorely wrong. Even someone that completely leeched to 50 can put in the time to learn a job perfectly afterwards, the two things are at best weakly correlated. "1/2 of the players" aren't crap because they levelled fast, they are crap because they are crap.
3. Honestly out of all the people I know with all 50s, none of them complain. I'm pretty sure SE arent aiming to make this game about the levelling up, they are going to make it about what you do when you get there.
4. Yes, valid point - almost. The game has now been out so long that even at a slower xp pace, newer players would still have been left behind. The only clear remedy here is some kind of level sync, but I don't know where I stand on that front.
5. Wait, what? This is just silly. It makes endgame more accessible given the horrific habit of the player base to class stack. Honestly, dungeons were designed with class swapping in mind, and newer content is locking job swapping altogether. When you are in Hamlet defence in your party of DoH and DoL, does the fact that you also all have Dragoon 50 which you cant even swap to really make it that much mind-numbingly easier. Endgame content is easy because the dev team hasn't managed to get content difficulty right yet - well they did for Garuda, and everyone avoids that like the plauge, regardless of if they AI exploited themselves 7/7 or not.
6. The accomplishment in this game isn't supposed to come from leveling, and rightfully so. I don't know about everyone else but I get a far greater sense of accomplishment from triumphing over a challenge than I do from knowing I have successfully sunk enough time into something to fill a blue bar 49 times.
7. Yes and no. A big YES in the case of behests etc, but Toto-rak is still frequently raided, and most of the low level content is "compulsory" anyway (GC/Job/Story quests). I think bringing behests etc up to the 50 level and adding some useful rewards (read: Seals) would be better than slowing xp or capping levels for them, I like having all of my abilities and traits >.>
8. Lol at trying to make 2 points out of one, see my response to 2.