To be honest I do wish they would fix the duds too. I hate looking through my collection and finding cards that are literally just taking space because I just cant put them in a deck. But if they attempted to fix those cards too, it would be too much errata to keep track of. Id love if they printed sets of new cards to replace old duds but I just don't think that's gonna happen.
I understand your points, and it is a co-operative game. So if you want to play at home, you can play the cards the way you like best. The only thing I would say is that if you attend a group setting ( Con of the Rings, etc) you should play the game as its intended by the designers. If I played at a table where someone was using pre-errata burning brand and blocked every shadow, I would definitely feel like a win is invalidated. And I think its proper courtesy to play the game by the rules when playing with other people.
But either way, it is cooperative and the aim of the game is to have fun. I don't want to spoil that.