First of all, I personally don't question either.
But I think the reason is because Kakashi's hype isn't completely limitless AND he has a possible explanation for it. The Sharingan IS capable of copying and memorizing techniques. This is a stated fact from countless times. And Kakashi IS a very experienced shinobi, having served in multiple platoons, wars, ANBU, etc. Lastly, despite all the jutsu, he has his limits: he can only use the Sharingan so much before his body gets exhausted. This makes his hype not so out there.
Compare all that to calling someone a god of an entire society... Then kill them off in the first and only fight we've seen them in. It makes people unsettled with such a huge claim and so little to show for it.