The hate for the fatigue system is mostly based on misunderstanding of the concept. I'll try my best to explain as I understand it as the developer's have stated in the beta forums. If something is not clear or is confusing, please let me know so I can elaborate further.
First, there are two types of experience. One is called skill points, which only level your discipline or job and experience points which are for your overall level. Everytime you gain an experience level you are rewarded with points that you can distribute on your attributes and elemental resistance categories.
The way it works is the developers have calculated how much experience and skill points someone would gain in an hour. After eight hours of nothing but experience point gaining your character will become fatigued and can no longer gain experience or skill points. So, for the sake of arguement let's say that predetermined number for an hour is 5,000 and for eight hours the total is 40,000. After gaining 40,000 experience and skill points you can no longer gain anymore. And the 40,000 EXP fatigue limit is reset weekly. So, depending on the amount of experience someone gains they could essentially never reach the limit for a week or they reduce their fatigue in a number of ways.
Reducing fatigue means you would have to stop gaining experience by focusing on quests, storyline, crafting or anything else. Example: let's say you gain 20,000 EXP in four hours and the game has your fatigue at 50% then you decide to go out with some friends and do not resume playing until the next day; because you stopped gaing experience the game now has lowered your fatigue to 30%.
Now, let's say you reach 100% fatigue on experience points and skill points for the discipline of Lancer. You can also switch to another discipline (Fisherman) and continue receiving skill points on that as normal with no fatigue. Let's say you reach 100% fatigue on Fisherman and because you were not gaining skill points on Lancer the fatigue on that discipline has been reduced to 0%.
Overall, if you switch up your playstyle and do not focus on one discipline or activity then you may never reach the 100% fatigue on anything and play without ever having to come into contact with the fatigue system.