Back when I mained a Feral me and the Feral community (which back then was quite small) always cried and hoped for Shred to remove it's positional requirement. It's completely unfair Ferals are gimped on any boss like Ultraxion with no alternative besides tanking. You would either have a crappy DPSer or a tank who doesn't want to tank, neither are very attractive for a raid leader and creates weird situations in raids. Thankfully in Cataclysm they addressed this issue by improving the damage from Mangle instead.
Removing the positional requirement on Backstab would feel very wrong from a lore perspective. You can stab people in the back from their front? Does this mean your Rogue will walk up to your opponent, give them a friendly hug, and then stab a dagger in their back? It just feels wrong.
From a gameplay perspective removing the positional requirement would be a big quality of life change. It would not make Rogues feel like they need to go one of the three specs for fights like Ultraxion. But at the same time, we have a choice whether we want to play a spec that requires the use of Backstab or not. It would also remove quite a bit of skill from the PvPers out there if we could just Backstab whenever we wanted to. I have very mixed feelings about that, lore aside it would be amazing but at the same time will dumb down the class even more.
I don't know. If they come up with another boss like Ultraxion I will most likely cry myself to sleep at night if they don't change it. But since Dispatch* doesn't have a positional requirement and Backstab will become a Subtlety-only ability I don't think I really mind.
*if anyone is unaware of it, Dispatch is Assassination's replacer for Backstab in MoP.