It's not allowed only because it's not allowed. Console users should also be able to benefit from the creativity of modders, and LBP showed you can make money by allowing this.
As for my original question, though, thanks for the link. Gonna check it out now. Is my game, account or PS3 at risk if I jump into one of these games? If the other thread covers that, I suppose I'll find the answers there. >.<
Thanks for the help.