I think the "randomness" is Diablo games is what makes it really addictive. I remember playing Diablo 1 and I couldn't stop playing because I couldn't wait for the next item to drop.

Also, a low-end machine could run it!

Diablo II, still the same thing - it was basically a better Diablo I.

Diablo III on the other hand came out with an Auction House - which basically killed it. I played in the early parts of DIII, it was okay but not as fun as DI and DII. However, things are very different now. There have been lots of updates in Diablo III and Blizzard killed the Auction House - So can't say how it feels now. But I'm pretty sure the "randomness" is still there - which basically what drives the game.