Pretty much agreed. Couple thoughts.
1. I haven't played through a previous edition change, but I suspect cherry-picking which new rules to play and not will become very unpopular, especially since WYSISYG is more important than ever. You would anger players quickly by banning fortifications or allies if people have built their armies to include them.
2. Allies are fluff now, by nature of GW putting them in the BRB. So arguing that BA and Necrons allying or whatever is against the fluff is no longer valid. The fluff has changed. Deal with it.