I feel that the reason for this is a combination of a number of different factors.
First we have elitism, some individuals feel that they know how the game SHOULD BE RAN, and heaven help all who do not agree, For the record I see ALOT of his on the boards on the min/max side (Why would you give your combat mage some hacking abilities). In all fairness the other side does it as well, but more at the table than on the internet (You are playing a NAN sam, why would you do X).
Second: Different goals. We all play for enjoyment but people find the enjoyment in different ways. There is a book for the champions rpg (2nd edition) called Strike Force, inside of it is a description of a bunch of different play styles. I highly recommend it if you can track it down. I a nutshell some people play to win combats, others play to plunge the moral depths of their characters, others want to be the best in everything, etc...Each of these types of people "win" a different way.