The noble is definitely underpowered. The problem is not that the Noble doesn't open doors, but that social skills are only as weak or as powerful as GM scripting. That makes the bulk of noble achievements dependent on what the GM decides to do, and takes a lot out of the hands of the player. That is not the Sword & Sorcery way for the heroes.
That depends on your point of view. Personally, I like strong players (players who have personalities and goals for their character with good background material) and strong GMs. A game doesn't succeed or fall on the GM alone or the PCs alone, it's a group effort.
I guess the point for all of this is that everyone should sit down and figure out what kind of campaign the PCs want to play in and what kind the GM wants to run. then they figure out restrictions or whatever on PC classes (no Kushites or Stygians, no nobles, nobody from Khitai for example) and try to place those characters INTO the agreed upon campaign.
It's all about individual taste and "flair" I guess. Nobles can be very handy. They (like anyone else for that matter) can be in the wrong place at the wrong time.
PCs shouldn't let themselves be led by the nose by a GM and the GM shouldn't allow himself to be trampled over by hording players. I think and feel that the best games I've played in or run were built on consensus from both sides and a willingness to work together.