Let's say you're attending Tolfdir's first ever lesson. At one point he asks you if you know the spell Lesser Ward, etc. Let's say now you're many hours ahead that specific moment, and you know the most powerful version of the spell Lesser Ward. Question: does it bother you to have obsolete version of your powerful spells or you just don't mind it and set favorites? Because I know PC players have the chance to delete spells (permanently?) through console. I know it might sound dumb but I'm actually trying hard to know only the most powerful version of a X Y spell, even thought that requires the obsolete version to start out.

It doesn't bother me.

My Nord doesn't use too many spells, and those that he does are pulled from the favorites menu.

Unless you are constantly going into the spells menu to pick spells, I don't see what the major inconvenience is.

It bothered me on Oblivion, especially when you made your own spells at a low level.
It don't bother me on Skyrim for some reason, and I'm really OCD with my inventory

Nope. Just unfavorite it once you upgrade. For me, the Skyrim UI works well in the magic category - it allows me to pull up each school of magic separately, so that I'm not reading one continuous list.

Almost everything I currently use is in my favorites so I'm not bothered by the others.