I can safely say that at least for me, the graphical engine is not the fundamental part of a game.
Yes, it does need to look good, but what is more important is the art that originated the game in the first place. The attention to detail is fundamental and with the same graphic engine you can have both a fabulous looking game and a mediocre one depending on who made the sets originaly.
The D2 graphic engine is a little outdated but the screenshot still look great. Why? because there is a lot of attention to detail and the original art-work from the artists are realy awesome.
Another example is the world of warcraft graphic engine. Even though its aged for 5-6 years already, and honestly it looks realy bad compared to all the games currently, the game still has millions of players all over the world.
In sum:
Art+gameplay+story > Graphic engine
