What is it about the newer premium board you don't like? My biggest complaint is that, as a 2-piece board, it can slide apart sometimes. I solved this by using two small black binder clips on the sides of the board, to hold it together. Works pretty well. But I do wish it were all one piece.
That's a fair question and I appreciate your inquiry. It really boils down to a portability issue for me. I have two copies of the Master Set already so in turn, I obviously have the two boards necessary for that should we ever play with more than two players.
However, my regular SW opponents live a little ways from me and I am typically the one travelling. If I wanted to just grab a few faction decks or maybe a starter set and pack up and go (without having to haul the large MS box), the older premium boards fold down more and allow the game to be more portable for me.
Do I like the fewer folds in the new premium board better? Yes...and I do agree with you in that having a one piece board would be ideal too.
But the more folds allows the boards to be more compact and when travelling to meet up with my SW opponents, I'd like to have the smaller premium boards as an option.
I hope that helps to answer your question.