I’m pretty sure that your first point (the one about everyone being terrible at the game in 2004-5) is the most important thing here. People didn’t understand a lot of what was going on, and that goes for both players under-performing in certain classes/roles and also other players evaluating what was good or not.
Players going back into classic with those types of class prejudices are going to be shocked when they run into holy pallies who actually crush meters because they have been getting better at the game for the last 15 years. I think its all going to work out pretty quickly.