This is a complete pet peeve of mine, for the reasons already described above. Follow school bus rules: let the people in rows ahead of you clear completely before you get off. Of course, if someone stays seated and tells you to go ahead, it's OK to go ahead.
It drives me nuts when I see people pushing past as people in rows in front of them are still trying to clear. This is one of the reasons I don't like sitting in the middle or window seat.