I'm sure we can debate every group to decide where they fit in and I might agree with you on many or most of them.The point is something you just brought up,why start a new category if it gets no traffic.I think Modern Rock would get a fair amount of traffic if given its own category .Like I've said before,putting groups,like Halestorm,into AOR or Hard Rock will probably get no posts because they would get lost among other groups.Just look at the categories and you'll see that AOR and Hard Rock has more topics and replies than all the other groups combined ! That's where the traffic is.Take Prog Rock-114 topics in 6 1/2 years and 113 topics in the same time frame for Christian Rock.That's not even 2 topics a month for those categories.
Like Glen said most of the newer bands get discussed in the AOR/Hard Rock category but that category is inundated with topics and replies.Why not break it up a little.And let's find out who's listening to modern rock.I know in 2013 Avenged Sevenfold and Five Finger Death Punch put out great CD's,certainly worthy of being mentioned in any top 5 list.I know they made mine !