I agree with you about the so-called 'perfectionist' tag the media has given Aamir. It's no different from the 'chirpy' Chawla, 'ravishing' Raveena types of adjectives. Though I have loved Aamir in many films, like you pointed out, Aamir is nowhere near an actor like Hassan or the now-big Tamil star Vikram when it comes to perfection. Just watch Kamal as a ventriloquist in the black & white Avargal, his transformation in Nayakan, as the palghat brahmin cook in Michael Madan Kam Rajan, as the blind violinist in Raja Paarvey (just look at the way he plays the violin like a pro and compare it to the way King Khan holds the instrument in Mohabbattein) or the subtlities he brings in playing almost every character even in the most absurdest of masala films...
Watch Kamal in the following original films and compare to Anil Kapoor's performances in their Hindi remakes/copies to see what I'm talking about...
Swati Mutyam (Telugu) and Eshwar (Hindi) Sakala Kala Vallavan (Tamil) and Abhimanyu (Hindi) Thevar Magan (Tamil) and Virasat (Hindi) Sati Lilavati (Tamil) and Biwi No.1 (Hindi)
(BTW, before you guys start yet another North-South fight here, let me state that I am not South Indian, but consider myself a film buff. I have enjoyed many Tamil, Telugu and Malayalam films courtesy my Southie friends)