…someone who already has experience using a program is usually better at testing/reporting bugs for that program compared to someone who just now got his hands on it…
When testing, you need input from every kind of user, from the experienced to the casual, so you can fix things on every level. A new user wouldn’t know how to fix an experienced player’s problems as a an experienced player sometimes wouldn’t quite know how to fix a newbie’s problems, because he’s simply in too deep in gaming to actually have the needs of a new gamer in terms of interface / gameplay.
But as the other guy said, now it’s more of a marketing tool. People do give their feedback, though.