I think a lot of the complaining going on is silly and the thought of a change from the norm is scary for a lot of people. I think it is great, because we are seeing something different than the stagnant and lazy chemistry of MMOs released since the early 2000's.
This has nothing to do with the chemistry of the game. It's simply a penalty for not "mixing it up". I should decide whether or not I mix it up, not the company I'm giving my money to, right?
Ask yourself this as a general question. Do you honestly think that you will reach this threshold of exp to the point of a 0%? How much actual time is that with the incorporation of everything else you can do in an MMO. It's a part, not its entire essence.
When EXP lowers even 1% from the base rate you are wasting time. Therefore, by their system after an estimated 8 hours you will be wasting time compared to if the fatigue system was not in play. Spending 8 hours a day in FFXI and WoW for me was childsplay and leveling 8+ hours a day in WoW was pretty standard when I was leveling up. I did what I wanted to and leveled up. It's not about what you -CAN- do, it is about what you -WANT- to do, in totally an events related topic (not talking about, "I can do what I want? Fine. HAX!"). It'd be a better fit if it was daily, but weekly people like myself would just destroy the time limits and paying for a game that a company has limited our options to what we can accomplish of our goals is not going to happen.
So far everyone I have talked to in beta have not run into an issue with exping on their main jobs. I think most people are jumping to negative conclusions too quickly without all the information they need.
No. People do not want to be punished for doing nothing wrong. People play games to enjoy them not to be told, "Hey, yeah, I'm really glad you like our Mage class and all but we also made a Tank, go play it or we'll have to fine your time, thanks and <3 -SE"
Also, the given reason for the "fatigue" is ridiculous. In essence it is punishing hardcore players for being hardcore to allow the "casual" gamer a more -fair pace-. This whole sentiment of making something -especially- for the "casual" gamer to be on par with the hardcore is retarded. It's a kin to someone who dropped out of high school and thinks their employment worth is that of an Economics graduate of Harvard University.
Finally, I'll say I don't buy their reason I just stated above. In WoW the majority of the players level up quickly, which you do in these types of games, and leave. They may leave forever, for a few months, etc., but they do, they stop paying forever or for an unspecified time, they are not steady money counts. This system slows down that process of leveling and leaving.