I never denied that leveling gives a learning experience. However, it is not required. It takes less than 30 minutes to learn to play a job you've never played before at 50. Read each skill, research a rotation, make improvements if you can, etc. The game does not have a vast amount of skills. Even in FFXI, most of us burned jobs from 30 to 99 post-Abyssea and we still played our jobs at the highest skill level. Once you've played the game enough, learning new jobs does not take nearly as long as leveling does.

Also, you are in denial if you think MMOs are about leveling up. The only time that applies is Korean Grind MMOs. If the goal is to level up, it becomes difficult to design endgame, and is generally ignored.

Consider it this way, it takes much longer to max every job in XIV than it does to max a single character in any other modern MMO. If you only had to level once, then I would whole-heartedly agree that leveling is too fast. This is not the case, though.