Wow, a legitimate critique of this band...and one I would have to agree with.  If you look at most of the stuff where they tried to push the envelope (technically speaking), they flopped.  Most of their stuff was not "psychodelic", and where they did attempt to go there in the early days, like "What's Become of the Baby", it was a flop.

The "jamming" was inspired by what Coltrane had already been doing, and the rest of the songwriting, where they really hit their stride, was rooted in folk/traditionals.  However, I still think they did cover some new ground, in the studio and live, by being experimental.

I think the observation is because the Dead always struck me as having a lot more unassimilated 19^th century folk and early 20^th century country influences in their music then a lot of other bands. Some illustrative contemporaneous examples from the same cultural genre might be Frank Zappa, King Crimson, Santana, Yardbirds, Moody Blues, Yes, Beatles, and Jimi Hendrix to name a few. The Dead just seems to lack the edge that many other musicians were starting to explore at the time. Just my 2 cents.

I know there are many who appreciate this band but their work is just so 19^th century chic. This will probably be a violation of standard orthodoxy but the GD are far too ultra-conservative for my tastes.

I dunno, call me a heretic if that helps.