Being as your point about higher AI population is the only valid, non-preference related benefit to PC exclusivity, I don't see where "much, much better" comes into play.
I guess you didn't get the car anology. You can't just say "oh, besides the UI, controls, graphics, what can be better?". I'll iterate, in a game with the number of options, menus, screens, etc as Skyrim, the user interface makes a HUGE difference. HUGE! You may not know what is a proper PC user interface in a video game because you play on a console, you may not have experienced what is like to play a game like Skyrim with a proper PC user interface, but I do, and I have. A fluid user interface adds a lot to the game experience.
It's simple, really... a game controller has about 10-11 buttons. A standard US keyboard has 104 keys, plus a standard mouse (now that's 2 controllers, KB+M)) has 3 buttons. My mouse has more buttons than your standard game pad. It just gives you so much control, it makes handling inventory so much better, equipping armor/weapons, alchemy, etc etc etc.
As for graphics... I am still playing Witcher 2... I look at Witcher 2 and its 2048x2048 textures, and compare them to the 512x512 Skyrim textures... guess which one looks more like you are in a desert, or you are in a rain forest... or the number and quality of animations in Witcher 2, then look at Skyrim animations (should check the dragon flight in W2).
... and let's face it. the content in Skyrim is not that special...
So, again, you question equates to asking "besides the interior and the exterior, what's better in a Mercedes as compared to a Yugo?".