From my perspective (as someone who started playing in 3e, and never played a 1e or 2e game) the 2e 'feel' was one of expansive, incredibly rich and detailed campaign settings, and to a lesser extent, a push towards linked and longterm plots rather than just single adventures, and a move towards style, flavor, and DM empowerment at the expense of the explicite rules. That was what I gathered anyways, though I've never played within the actual ruleset of 2e, which as I understand it was a bit obtuse at times.
I could care less about rules, so that's not a part of 2e that I'd want to bring back; rather I'd like the non rules material, the richness of the settings, and the stylistic elements of 2e design philosophy to show their face more often. To me there was a feel of wonder and richness that I never gathered from the 1e material I've read, or as much from the 3e material from WotC as I've found in the 2e Planescape, Ravenloft, Dark Sun, and FR material.
You just don't find that in 3e material. You now see a reduction in setting detail so you can put in some more feats, PrCs and 'crunch'. Crunch doesn't inspire me, and I doubt it inspires many people. And so now, an edition later, I'm finding incredible use out of old 2e books for their flavor and detail, and I likely still will in 4e when my 3e books are largely relegated to obsolescence with the change of the ruleset when their crunch is useless, their rules irrelevant, and their typically thin fluff won't hold a candle to the 2e books.
Others may feel differently. Most of the anti-2e feeling I find is by disaffected original 1e players, the substance of which is certainly debateable, but best saved for another thread. And also, perhaps in their defense, keep in mind that I'm looking back on probably only the best aspects of 2e, when its ruleset might have had flaws worthy of valid criticism. The design philosophy and flavor though were often brilliant, and it's a loss to see a reduction in their influence in 3e with a romantic resurgence of 1e ideals in some products.