I don't think all items in Diablo had fixed stats, though... they didn't in Diablo II, anyway (which I remember details of better than with the original).
In any case, I don't really see a big difference between randomly generated equipment and fixed equipment that is dropped randomly. Diablo invented reloading. The entire game is reloading. People have spent hours / days / months reloading looking for all the pieces of some set.
In DD the range of possible stats could have been narrower, especially for the dragon armour and holy sword, etc. While relatively unlikely, when reloading these items you could see fairly crappy results occasionally, mixed in with OK, good and very good versions. With a more consistent item quality people may still want to reload to get a specific stat (ie Frost), but you wouldn't have to do so to get something decent.
If there was some way to create or commission equipment, I think that would be good enough that most people would not feel they had to reload to get good stats on equipment. You would have to fix the drops and stats to eliminate reloading, anyway, which causes different problems. In Siege of Avalon, for example, you could only get what opponents were actually carrying after defeating them, minus anything that was damaged too badly during the fight. If you defeated a few weak enemies, you could equip yourself like a weak enemy. Each stronger class of opponent offered the possibility of new equipment upgrades, but most of the time you just kept seeing the same stuff over and over. At first you can haul this stuff back to town to sell, but eventually the price drops (supply and demand) and it isn't worth it to bother. Eventually I stopped even checking opponents to see if they had anything new.
There are games that have opponents just drop gold, or appropriate raw materials, etc. This could eliminate reloading, but at the cost of possibly making combat less interesting. With random drops, hack and slash portions of a game may get boring (there is no way to balance a game perfectly for everyone), but at least you know some of the opponents may drop something handy, or at least helpful.
The equipment / item system also depends on how the rest of the game is designed. With a lot of opponents and a hack and slash focus, you pretty much have to have random drops. With fewer opponents, specific drops are fine (maybe preferable) because there are not enough for it to become repetitive.
