On one of your points...MMOs cost a whole lot more to run than FPSs. MMOs require constant content upgrades to stay competitive today, particularly those that have heavy PVe areas. Without that content upgrade, no MMO could compete in today's environment.
As for experience point scrolls messing up people's ability to play, I wouldn't worry about it. It won't save that much time, the scrolls last an hour and people would have to put ridiculous amounts of money into them to keep them up through the whole process. The idea of them, for the most part, is that they'd be used by people who don't have a tremendous amount of time to play, so they can catch up to hang out with friends. I doubt any other use if really viable.
BTW, they don't affect competitive PVP AT ALL, because everyone in competitive PVP is automatically leveled to 80 and has everything unlocked already. This means that in competitive PVP you're really not learning a bit at a time, you're learning on the job like everyone else.
But it won't be different from any other game. There will always be people who take the time to learn their class and people who don't, scrolls or no scrolls.