It just annoyed me in 3 when they cut you off at level 20 with no hope of leveling past that. That kind of killed the game for me at that point as it felt useless to continue. I was having a lot of fun up till that point, but was dismayed when I found out there was a level cap. Honestly, I have no idea why they would do that. You could argue against becomming much more powereful then the NPC's, but that should be my choice. At least at level 20, offer me a chance to continue leveling or not, but let me decide--not Bethesda. There is vast territory in 3 that was open ended, and you would probably hit 20 well before you've explored everything. Just my opinion.