The latter. There are not enough products for even a semblance of a unifying style to form.
I'll disagree with your reasoning. There's some commonalities between the likes of Risen, Gothic, Two Worlds, Divinity 2, and even The Witcher for a subgenre classification.
...no? You've cited wildly different titles, half of which aren't Eastern European anyway.
Origin is irrelevant to the classification. You don't class games by origin, but by similarities of game content and/or play. If you have a better name for the class, I'd welcome it.
And I'll disagree that they're wildly different. Though my play with a couple of the titles wasn't thorough.
Because it's painful to admit just how few RPG developers aren't developing in that style. Three, and they're all American. Don't take away my denial! Well, then there's the diablo clones.