As someone who spends about 3 hours a day on trains, I couldn't care leas about people having their feet on the seats. Obviously not if they are full of dogshit, or if someone is sitting on the same seat, but if its empty and people have cleanish shoes, really doesn't bother me.
I'm more annoyed about those that leave litter and their half-eaten food, empty cans, chewies under seats. Or that are too drunk and sick on the floor or the seats. Or have a wee, seen that too.
There is loads to be annoyed with on the trains, someone putting their feet up isn't one of it for me and its redicolous they're going after it that much.