Crimea was in the USSR, no? So it's been 30 years since the area which is now Russia had control of Crimea. I have no idea how long ago is too long, but probably a human lifespan maximum is reasonable. Part of the calculus I'm using is literally just "can the country win a war for the area?". Which is why Alaska is not debatable. Like, Russia really wants Crimea, they will most likely win the war eventually, why not let them have it if it means ending the war? If they were to then try to take more land, that's when we put our foot down. Sure it's a bad precedent, but who says we have to follow precedent? It's really just America that cares about Russia not getting stronger, the rest of the world should want all of Russia, China, and America to be roughly equal.
If Alaska is a great starting point for invasion, then we definitely should not let them take Alaska.
It's not though. It's strategic importance is purely defensive. It is useful for influencing places that border the black sea. It's completely irrelevant to an attack on anywhere else