They definitely could have done a hell of a lot better, but any show that's this popular and gets drug out to 8 seasons is going to be incredibly difficult to manage. At that point you're no longer working with hungry actors who are thrilled to be working with HBO. Now you're dealing with pampered celebrities with a hell of a lot more leverage and who are getting paid a shit ton more chewing up the budget and many have some sort of influence over the creative direction of their character. Yeah, on paper it wouldn't be too hard to write something a fuckload better than what we got, but when you have to take into consideration everything else that goes into producing the show, i.e. Cersei won't work with Bronn, x actor's contract requires x amount of dialogue, nobody wants to do nude scenes anymore, x actor doesn't think this scene fits their character and wants it rewritten, etc. you can see how it can easily turn into a giant fucking mess.
