Artists that use the same song structure...

A few more come to mind - Norah Jones, Alicia Keyes, Enya

Remember when Mick Jagger sang "It's the Singer Not the Song"? When I was younger I strongly disagreed with that sentiment, putting the song way above the singer. Hence my love of The Beach Boys, precisely because they had the best songwriter in the world (Brian Wilson), but only okay singers (except for Mike Love, who was/is dreadfully bad).

As I've gotten older, my thoughts on the matter have changed. And though the song still comes first, singers are of much more interest to me than they used to be. Iris Dement, Emmylou Harris, and Allison Krauss from the gals, John Hiatt, Buddy Miller, and Jim Lauderdale from the guys, being amongst my current favorites.

Pop music songwriting took a giant nosedive in the 70's, when Rock Group's songs became not much more than a guitar riff. The "sound" of a Band became their "song", what they were known for. Bands like Alice in Chains have only one song, really, every single one even having the exact same two-part harmony (and it is not a very good one). Boooring!

All blue grass music has the same song structure and melody.

By definition, the vast majority of blues tunes performed by singers like SRV will have the same "form"; the classic "twelve bar blues". What distinguishes one blues song from another is typically the melody and the time feel; the "form" is usually (not always) exactly the same. The two songs you mention not only have the same form, as is usual for blues tunes, they are in the same key, the melody is very similar and the tempo is almost the same ("I'm Crying" is slightly slower); those are the things that make them sound so similar.

SRV is a blues/rock singer and his musical palette is fairly limited. I don't think that the fact that many of the tunes he performs have the same form is any sort of indictment of him as an artist. I do think that those two tunes are so similar that it seems almost ridiculous, but not terribly surprising. I do think it is an indictment that he is not able to do something with the interpretation of each to distinguish one from the other.

Some of the other artists mentioned do sound very similar from tune to tune, but those tunes don't necessarily use the same "form". "Form" is not the same as "formula". Actually, a better way of looking at this issue, and a great test of an artist's true talent, is wether an artist can sound fresh and interesting IN SPITE OF the fact that his/her tunes use the same form.

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.