I think the sideboard changes are interesting and mostly a non-issue but as a person who received a game loss once at a PTQ I'm for it. I only play MTGO now so it really doesn't affect me much but I am interested to see what (if any) sideboard changes are coming in the future.
Are there any legendary commons on mtgo? No? I didn't think so. So this doesn't affect pauper at all, but it will have an impact on Modern. I had intended to play Modern after the MM release. Not so sure now. I guess I'll see how it plays out, but it feels like mtg is getting dumbed down again.