I played all of them, Gothic 1 and 2, and Morrowind as well. Gothic first, since it came out first.
I replayed the Gothics a dozen times since.
I never replayed Morrowind, although I spend about 2 years playing it in a row, intensely in the beginning, sporadically towards the end.
What I figure today, that the magic of Morrowind for me was the setting, and the sandbox free roaming exploration. I have had that in Gothic 1 before, but not to this extent. But if those things hadn't grabbed me about Morrowind, I would never have played it to the extent I did. For me, thus, Beth design only hits the spot if their atmosphere and world is captivating. Neither Oblivion nor Skyrim did that for me.
But I still replay Gothic 1 through 3 these days. They are probably my favorite games of all time. So they are classics for me, and I know for lots of other people (almost every gamer I know). But they were niche games even back in their time, with a less known European developer. Does that mean they can't be classic? Can only more streamlined, more economically successful games be classics? I don't think so. Design makes a game a classic, not the number of players who played it, nor the market, and especially not the North American market. I know you don't like to hear it guys, but not everything about NA.
As for this bundle that is the original topic, I'll say it again, Gothic 2 Gold is the only thing from it that is worth it really. And I recommend buying it from GOG rather, along with Gothic 1 and vanilla Gothic 3. Those are the real gems.