People dont like it....but its a design choice that keeps players playing.
The faster you get what you want/care about, the less time you play.

"Just make more content"
Well 2 issues, we would have much larger content droughts because theyd have to take extra time to develop it, and NOT releasing it until they finish everything and then release it all at once.
And even if they DID do this...there are people who have nothing better to do and spend all hours in a day playing the game, and will run through everything in a few days or less.
So this is a better system.