It's not really hatred. Rust is just a fairly mediocre winger who isn't a play driver and isn't really an all-year player. Even the best defense of him is "he was good yesterday and not bad since a month or two ago", which isn't really a ringing endorsement. He's a decent trade piece and a complimentary part, with a bad NMC. He's known for being streaky and not bringing his effort to the game constantly. What's wrong about that?
I don't know what Malkin has to do with it. Rust was bad in G-Crust. He's been streaky for YEARS. Acting like this is some new fad is weird, considering the board is littered with criticism of Rust's bad play over the last several seasons.
I dunno man, you can accuse me of a lot of things but I've consistently been frustrated by Rust's streakiness for pretty much 5 years or so. I'm at least consistent there.