Bands I'd love to see as DLC for Rock Band:
Bal Sagoth 
Like Soror_YZBL I think it was primarily a matter of the Pistols being so high profile and staging plenty of events to flip the bird to the general public (swearing on national TV, the riverboat concert) whereas the Misfits were underground. Everyone knows who they are now but most of those original records had tiny pressings that have been highly prized since the mid-80s and only after Metallica brought them some small amount of popularity did they start to repress their stuff for the masses.
Its not like we didn't get the PMRC with dozens of bands under the microscope. Dead Kennedys certainly managed to get plenty of attention to practically get sued out of existence in their prime.