I can add a custom title.
I recall in ST enterprise that they gave a reason for Klingons who didn't have any brow ridges was due to a based on an enhanced human genetics plague that had ravaged the empire and the cure made the ridges disappear.I agree, but that doesn't mean they all have to look like Michael Dorn! I think they were trying to solve the whole question of why they've looked so different over the years by explaining "there's a lot of different looking Klingons." (Same with Romulans in Picard). Problem is solved going forward, IMO.
Of course, Truth Seeker might say that it's because they didn't want to pay for the license to use the definitive Klingon-look. Maybe that's true!
In a DS9 episode where they went back in time they asked Worf what was up and he said it was a difficult time in Klingon history which they don't like to talk about.
They've (the writers of the various shows) have definitely thought about the differences fairly early on.