I'm going to respectfully disagree with you.
The Perk/Skill system is hardly the selling point of the game. It is part of it, but not even a major part. The open world RPG, exploration, etc. are much larger parts of the games' success than the Perk system.
open world and exploration are definitely the primary selling points. but, in general, i assume that people on this forum are well beyond those as 'selling points.'
i know it is for me. it's expected. it's required. it's a given.
regardless of that discussion of opinion, the perk system and leveling what you use are the 2 major 'selling points', attributes, whatever word you'd like, of skyrim when compared to morrowind and oblivion.
and, for such a huge part of what makes skyrim different to be so flawed, yet, accepted, doesn't work with me.