I think Seinfeld was a very well made up sitcom and the first season was very humorous to say the least. However the only MIDI I know of is the tool that is used to translate the sound of music in to notes and why would Seinfeld's theme be used for that purpose?
Yes, the MIDI theme of Seinfeld's first season was funny, because it reflected the music that was used during that time. Music like that was common. The theme was catchy. It obviously worked, because the show went on to become very popular. It was a good choice, and it was similar to the style of the show.