I'm looking at it with a cooler mind. It shows all signs of an overproduced, overhyped, uninnovative product everybody will buy anyway because, hell, it's Blizzard and it's Diablo! I call it the "World of Warcraft Syndrome" which isn't to say that WoW is bad - it's good, probably the most polished and accessible MMORPG of them all, but that doesn't mean that there aren't better and more innovative titles around.
I mean - listen to the annoying music that tries SO HARD to sound epic. Also, it seems that the skills, environmental interactions etc. got more complicated yet again and the lack of "purity" in its hack&slash-ness is what made me not play Diablo 2 to the extent I was playing Diablo 1...
Nevertheless we'll have to wait for the final game - I really dislike hyping or dissing games (which, I believe, I just did - just to counter the enthusiasm) before getting to play them especially since, being a video game journalist and all, I see them long before they are released on some occasions and thus am even more annoyed by all the speculative crap many people are saying about them. ;-)
Diablo was back there a really great hit. Played it a lot in our good old 10Base2 network. It was a really new thing. You cannot understand its fascination from a "modern" view on games. D2 is based on this effect.
I think you pretty much nailed it by using the past tense and referring to "back then". Will it still be as exciting 50 Diablo-clones later? Does everybody always want only more of the same?
Basically the way I feel about Diablo 3 after having seen the gameplay videos is pretty much the same as my feelings towards StarCraft 2, which seems to stick maniacally to the "old ways" so as to not upset fanboys but at the same time not innovate too much. I'm a guy who prefers fresh but flawed (of course in the best case scenario they shouldn't have flaws =) titles to the unoriginal but polished ones...
P.S. I've been using my nickname ever since Diablo 1 - Lim-Dul, the level 48 Sorcerer (AFAIR it was pretty much impossible to get to level 50 without cheating in Diablo)... I still might have a character dump on one of my old HDDs. ^^