This may have been discussed before but

I am not sure if it has been mentioned but one of the things that's rather cool is that African american skin color can carry off colors of shirts that the "white" Caucasian skin color can't so well.

I remember first noticing this about 20 years ago or so. Purple, lavender, pink etc. for men's shirts started coming more into fashion as blacks moved into more middle- and upper-class professions. They were considered inappropriate for men to wear, professionally, until then.

Now, black professionals have made those colors more acceptable so even white males are starting to wear them -- though I don't think the skin color pulls it off as well.

It's been a while since I've watched any of the season 1 episodes so I don't remember that he specifically wore purple a lot but I do remember that you don't see Lavon in plain white very much throughout the course of the series. He wears blue a lot too.

I don't remember them ever discussing Lavon's color choices on the show but it has certainly been addressed in plenty of fan-fiction stories :)