Trimmed and boiled down, the problem with the leveling system is that, as many have mentioned, it simply outright punishes you for trying out all of the game features.
I don't mind that you get punished for trying to be the God-King of every aspect of life.
However, I do mind that leveling non-combat related skills is actually detrimental to you. Like, if you could get through most quests by specializing in speech/lockpicking/pickpocketing/etc etc, then I would be like 'Okay'. But you can't. If you aren't a full/almost-full combat build, you're screwed.