Lack of End Game Content

[linay]

the feeling of having to meet the cap within that set period or end up feeling behind.

Since we're speaking endgame, at that point, they should know enough about the game to maximize their playtime and what they want to accomplish in the game without having to feel left behind. Another thing to consider is that having no cap means that you can be left behind even more and then having the pressure to overcompensate when catching up.