The original books, as is well-known, do not have minimum ability requirements for the three (four) core classes (or for the races, either.) So, although the M&M character creation example describes rolling ability scores first, then selecting class, there's no reason not to do it the other way. I've seen some people mention even requiring players to select class first, then rolling for abilities, which other people have described as "hardcore".
I haven't done this, but I've considered it. If I were running a game for people new to OD&D, I'd possibly require it, to reinforce the idea that the scores don't matter as much as in other games or other editions.
Anyone have any experiences with hardcore character creation? How did players take it?