The EN World kitten
I can't back this up with anything except my own impression, but I suspect a lot of people felt that way. The Wikipedia entry for the show notes that Eric was depicted the way he was for a very specific reason:This isn't going to make me look great but as a kid I often sympathized with that guy. About half the time he was the voice of sanity and reason, and in a real D&D party people would have been fine with him!
Series developer Mark Evanier revealed that Eric's contrary nature was mandated by parents' groups and consultants to push the then-dominant pro-social moral for cartoons of "The group is always right; the complainer is always wrong".
I think a lot of kids were able to intuit this, and found Eric more sympathetic than the parents' groups intended.