There is a big difference between the OT type stormies and PT clones.
Well from an aesthetic perspective, yes, but on can throw a very similar argument that has already been thrown out against the R1 troopers, albeit a different form of continuity - Armor appearance "quality."
Through no fault of the ANH production, the prequels were made using CG over physical costumes, resulting in the ability to produce "perfect" representations of the clonetrooper armor that lacked asymmetry, warps, bumps, shins splitting apart, etc., essentially every known "flaw" of the original TK armor.
Now, the argument that is aforementioned, used against the R1 troopers, is "why" are these so much different from the original ANH armor if it's suppose to (allegedly) end up to 10 minutes before the start of ANH? Well, my argument is then why is the ANH armor so wonky and imperfect if it follows in the footsteps of the clonetroopers in episode 3?
Surely in universe, the armor's aesthetic quality didn't degrade after the Empire was formed, did it?
It's all semantics. So you know what I say to the "purest"? Get over it.