Artists that use the same song structure...

I was about to make Frogman's post - almost word for word. The observation re: the blues also applies (tho less precisely) to basic rock n roll song structures. Chuck Berry's song structures are almost as limited as haiku - and therein lies the art: Can you make compelling music within the strict limitations of the form?

I don't see this as a criticism at all. Creating within a norrow environment is not only an artistic challenge, but it's a challenge in which the results are often satisfying at a very basic and fundamental level. There's something essential (and, weirdly, "elegant") about a great rock n roll or blues song. In an even weirder sense, I get a similar sense of satisfaction from a well executed plate of sashimi.

At the other end of the same spectrum (and without drawing an equivalency to blues or rock music), Bach often works within a narrower range of expression than did later Western classical composers. I'd argue that his music lies within a sharply less expansive universe of expression than someone like Beethoven, yet I'd never diminish his work for that reason.

Sometimes, IMO the best answer is the simplest - and the simplest answer is found within the tightest limits.

I think it's fair to point out that "avant-garde" is hard to pin down when discussing music. Does Phillip Glass qualify? If so, he probably fits the OP's question reasonably well as much of his work follows pretty formal structural rules. Actually, while I don't profess much depth of knowledge of modern "avant-garde" composition, it kinda seems to me that a fair bit of it is formally pretty rigid, Schopenhauer is one that quickly comes to mind.

This isn't my listening hour "meat and potatoes", but I'll dip a toe in these waters from time to time.

Czarivey,

Doc Watson was a wonderful player, but Bluegrass is full of spectacular guitarists. Check out Jerry Douglass (primary guitarist for Alison Krauss and Union Station) or Tony Rice or Bryan Sutton, among many, many others. I understand that you may find the general tonality of the genre off-putting, but there's wonderful playing talent shot throughout the bluegrass catalog. You may not find it worth the effort to acclimate to the form, but - if you do - you may be pleasantly surprised by what awaits you.

Swamp,

Your point is taken, but a dobro is actually just one brand of resonator guitar. Like "Kleenex", I guess that it has become synonymous with the product type and the resonator is very often considered its own instrument separate from the guitar. Depending on the day of the week (or time of the day), I might do that myself. However, in this particular post, I was including Douglass in the broader class of guitarists. I understand those who'd put him in the separate class of players, but it's essentially a semantic distinction at the end of the day. Probably a little sloppy on my part, tho.