Maybe every class should get a little bit of choice when levelling up.
I know it's not in the holy book of 5e, but I'm an atheist so I don't care about holy books.
You can't be clever, decent and a magister. When you're clever and decent then you're not a magister. When you're clever and a magister then you're not decent. And when you're decent and a magister then you're not clever.
Have you played BG1/BG2? In most cases you didn't have anything to say during levelling up. From time to time, you could add weapon master point to the weapon or spend attribute points on thief, but that's all