Well, I dunno ... most of my pre-3.x stuff are very early
AD&D things written by the venerable Col_Pladoh, such as
The Keep on the Borderlands or
The Lost Caverns of Tsojcanth -- and what makes them cool to read is that distinctive Gygaxian style. The other stuff I have before 3.x is the Lankhmar material, which varies greatly in quality and a few of the "Complete X Handbooks," of which the one for thieves is excellent and the rest aren't worth the read.
As for 3.x, there is a certain genericness to the WotC stuff as reading material, I don't deny it -- the same way that most of the post-Howard writers of Conan stories seem very generic compared to REH himself. However, a lot of it
plays very well once you put your own spin on it, and that's more important from a gaming perspective, if not necessarily from a sales perspective. (There's a lot of older stuff that I bought just to read, knowing full well I'd probably never use it in a game ... Lankhmar being a good example.)
Some of it may simply be that
D&D isn't "new" any more -- it doesn't have that raw vitality of everything being an experiment and every idea being a new idea.
AD&D made gaming (relatively) mainstream, and 2e took it in all sorts of new directions, some great and some not-so-great ... but one thing it did was very thoroughly
explore possibilities. If a lot of 3.x seems "ho, hum," it's possibly because 2e had been there and done that.
3.x has yet to really find itself within the gaming culture, although d20/OGL is certainly having an impact. But even if the individual products don't have quite the same oomph (the adventure path started by
Sunless Citadel, as good as it is, is no
Against the Giants/Vault of the Drow), the system itself is much more robust, and that will only help in the long run.
-The Gneech
PS: Let us not discount the amazing power of nostalgia. In 10-15 years, people will be fondly reminiscing about what a neat character Meepo was and wishing these new expansion crystals had the same soul...