Isn't one of the beautiful things about "Trials..." that it successfully managed to boldly fit TOS-as seen in the 60s- in with the post-TOS universe? ("Relics" also comes to mind).
Plus retroctively made the ridged Klingons *somehow* fit in perfectly with the TOS Klingons because we now knew that, at some time, for some time, *something* happened to the Klingons.
Not quite as elegant as the "different tribes" approach, but perhaps the next best thing.
I think the STVI Klingons' appearance makes little sense (unless you accept ENT's idea and they slowly recovered from the virus). Like your idea, it would suggest that either what we saw on TOS is not what really happened in that universe, or that those bumps were already there in TOS, but we somehow didn't spot them.
Plus retroctively made the ridged Klingons *somehow* fit in perfectly with the TOS Klingons because we now knew that, at some time, for some time, *something* happened to the Klingons.
Not quite as elegant as the "different tribes" approach, but perhaps the next best thing.
I think the STVI Klingons' appearance makes little sense (unless you accept ENT's idea and they slowly recovered from the virus). Like your idea, it would suggest that either what we saw on TOS is not what really happened in that universe, or that those bumps were already there in TOS, but we somehow didn't spot them.