Was excited to hear today about this new feature coming with the Dark Brotherhood DLC.
Once your bounty gets high enough, it is basically permanent (20-30 million or so). At this point, it's challenging to do many quests, because invincible guards are often standing next to the quest givers, and some quests in interior locations seem perhaps impossible to begin.
It sounds like this disguise will make it possible to finally do all these quests. Been particularly wanting to do the quest to unlock crafting writs for some time, but previously every time I tried, I would get immediately rekt by the three guards standing next to the quest giver inside Davon's Watch mages guild