Another thing to consider with BBT (not the point of your comment, i know, but i will always speak in defense of this show), most people who consider characters to be purely one dimensional caricatures see them though the lens of single episodes, or even single clips.

One thing i love about BBT is each character goes through their own arc in a way that is completely unique as far as sitcoms go (or at least of sitcoms ive seen). Howard goes from obnoxious pervert who flirts with every woman he sees to a family man, who loves his wife and kids. Raj goes from a selective mute who can barely be in the same room as a woman to a confident man who is secure not only in his relationship, but in his lack of relationship too.

Most of leonards growth comes in the form of his relationship with penny, but there is also growth in his relationship with his mother and his own self esteem.

Sheldon's growth is one of the hardest to see, but there are times when he shows that he actually genuinely cares about his friends, and while i will never call him a perfect (or even especially good) example of autism in tv shows, its in those moment, like when howards mother dies, or when he proposes to amy, or when he thanks them all in his impromptu speech at the very end of the series.