Adding Double Bass and cymbals etc. Yes that will add to difficulty, but... If it's done right, once you add in enough drums you can then use actual drum tablature because you have all the pieces. The crime will be them not using the actual drum tab at that point.
When speaking to my son who does the guitar and drums and me being a guitar player of yester-year... Playing a real instrument you can rely on a certain sound always being in that certain place. You memorize, can pickup new songs quickly by memorizing where all the sounds are at, etc.
With guitar games, pressing buttons doesn't always have that logic in it. That is why it's very very hard to play a guitar game from memory, it's because it's not neccessarily logical the tab they give you for it. The same sound can be on any colored button, not always the same one. However I do think they start you on a path to being able to read music as you play it, but that isn't the rock worlds M.O., it's all based on memory, but still not a bad thing to know.
Today with RB drums you get the same affect (not as bad though), since your limited to 5 total drums some things just aren't mapped at all or logically on the games tabulature. But add in the rest of the drum pieces, they should without question (zero in my mind) use the actual tabulature.
Putting in the actual tab means you can rely on sound pointing you to the proper drum always. Now you can really memorize the song and not even need the screen after time, as every sound will be logically mapped to it's correct spot. If they do this, it will be a landmark release. There is no reason other then someone trying to hold us back for whatever reason. (Just read YRD's post: Yeah the issue is they aren't opening up more channels on the screen's fret bar (whatever the may call that). So as he says blue could be played by 2 things. That's holding back drum perfection.)
To Rhyvven: Right now I'm going to let him push himself in how he learns, he's doing a good job on his own right now. He's really into it beyond the game and towards actual drums pointing to a band. He's using the technology at his disposal at this time, programs, movies, etc. He is even a decent student of the drums at this time, learning the tech's and names and why you do this or that.
However I'm certain with a real teacher he can even learn more of the proper lingo and techniques. I just want him to push himself with what he has now, see where he's at and then yes try getting him to go to lessons. This isn't buying a kid an instrument he has zero idea in, doesn't know if he really wants it etc and then forcing the drums. This purchase has been a no-brainer because of his skill and his wants, he's the one focused, the right person to be. Thanks.