You'd have to be missing an extra chromosome to think Siege of Dragonspear is equivalent to a new game. The writing is cringe worthy, it's extremely linear and hardly has any choices in it which actually impact the progression of the story, and a few other things. They also rushed the ending, ruining that as well. It wasn't horrible, but it didn't even come close to Baldur's Gate in anyway. I said make an Infinity Engine game with a new universe, setting, characters, and an EXCELLENT story. SoD was none of those things, so fuck off with these bullshit arguments.
That's the thing though, we don't need another BG game. We've done enough in the BG universe, or at least, in that specific area of it. Make a new setting, a new universe, new characters, etc. That's what I mean by a new game. This is just one type of RPG, but I personally enjoy isometric RPG's more then any other type. If you enjoyed BG, IWD, and PS:T, another Infinity Engine game with excellent writing and a new story/setting would be another gem. If you didn't enjoy those games, then a new IE game wouldn't be targeted towards you.