Oh no what have I done? I started diablo

I agree with you completely on that aspect. Rushing does make the game boring, to me and you anyway. I like the satisfaction of knowing I leveled a character up, did all the quests, and found the gear. Not some level 90 who had spare time.

Leveling a character through all three difficulties gives a lot of satisfaction. Normal and Nightmare are pretty easy, but getting through hell by yourself can be really, really challenging, especially if you don't know what you're doing.