Nothing wrong with jeans and T's ,  and nothing wrong with " dressing up to go to work " either.   Great music should be enough . . but agree with KC's thought . . having a good  signature look that separates you from the pack sure doesn't hurt in what is also a highly visual market.  
Tina Turner fronting The Band  is perfect btw  . . .  probably just a coincidence that her  fringe dress is very similar to the black one Grace wore in Boston huh ?