playing bass on guitar is only needless if you have a bass. i'm guessing most people who have the game don't have a bass guitar and would still want to be able to play the bass arrangements. EDIT: sorry i thought you meant RS giving the ability to play bass with a regular guitar. i agree, playing the bass charts with a real bass is definitely preferable to playiing them on a guitar.
i agree with most of those UI criticisms and can think of plenty more too. one thing i kind of wish for would be a way to see at a glance my previous high scores and mastery levels for the songs in the library. i like being able to look at the RB3 library and tell which songs i've GS'ed, 5-starred, 4-starred, etc as well as my percentage, so i can tell which songs i need to work on. something like that in RS would be helpful.