Pinsky Was a Very Unique Character

In the first season all the kinds had their defining trait, and for the most part stuck to that cliché. Including Michael was the average kid, a good guy who would stand up the bully Budnick. Not only was the character of Pinsky an upgrade over Michael, but he was very unique character for any kids show at that time. For example;

He was a good looking rich kid, but he wasn't stuck up. Kind of cocky but not in an obnoxious kind of way.

Smart, but not a nerd. Athletic, but not a jock.

He was friendly with everyone, no matter how different they may have been. He was especially supportive of his bunkmates. He helped Sponge on his first date and with the newspaper. Donkeylips for the capture the flag game, and Budnick when he was crushing on Dina.

He knew how to gain favor with Ug, but wasn't a suck up either.

By having such a multi-dimensional character, it gave them the opportunity to give the other characters more depth than they previously had.