I think, to some degree, that it's often more important to stick to the spirit of the original stories than worry too much about making it all fit together seamlessly. So, the Klingons are always ferocious-looking, the Eugenics Wars always take place in the near future, and "today" always looks like today, and, eventually, World War III will take place sometime further down the road, while the stories themselves basically remain the same, allowing for a certain degree of artistic license.
Which is how movie and tv series alway worked, at least back in the day.
At it happens, I recently watched SON OF FRANKENSTEIN (1939) from the umpteenth mind. SON is the third of the original Boris Karloff movies and the direct sequel to BRIDE OF FRANKENSTEIN. Is it 100% consistent with previous two films regarding matters of art direction? Not at all. Does it retcon some details from the previous films? Absolutely.
Does it matter? Not really. And certainly I've never seen anyone argue that SON is not "canon" or set in a different "timeline" or a "reboot." SON is the third film in the Universal FRANKENSTEIN series, period.
At the risk of showing my age, I like to think there's something to said for not being too much of stickler about such things. We're talking theater after all.