I think you are trying to make the Portal games a bigger thing than they need to be.
They’re supposed to be small, fun, non-complicated games with light-hearted plots and obviously self-aware parody/satire style humor and what you wanted was a serious, complex sequel with breakthrough innovations and additions which would only make it a completely different game that happens to have a portal gun in it.
Now, I’m not going to argue with what you think of the actual Portal 2 game, however I can say that you were predisposed to be negative against it because it did not fill your own expectations for a sequel to Portal.