I never notice what tense authors use unless it starts to conflict. Yes, I realize how that sounds but I don't read fic to do literary criticisms, I read fic for its cracktasticness. Forcing myself to write in the past tense is just what you said, stilted. I prefer the flow of present tense, I like how it draws you in quickly so you read fast and then faster and you're in the moment with the characters.

But, that's me. ::shrugs:: I think you're right that some people think past tense seems more authentic or valid or just plain proper for fiction