No, blues players aren't undervalued by society. When you consider how little they contribute to the overall quality of life, it's a miracle they're thought to have any value at all.

You see, blues players play music that makes you want to kill yourself. The underlying message of all blues songs is, "Life sucks. Yer woman's gonna do ya wrong, yer dog's gonna bite ya, and yer gonna git an infection that's gonna make yer dick fall off. Gettin' hold of a bottle of rot-gut whiskey an' drinkin' yerself to death is the only way to solve yer problems. Do it. Just be sure to tell yer best friend that ya wanna be buried in some cypress grove and that he should see that yer grave is kept clean. But it won't do no good 'cause that same best friend's been bangin' yer woman for three years now, an' he'll be glad to see ya gone. Why should he give a shit about how clean yer grave is?"

Of course, blues music is not the only genre capable of making listeners want to commit suicide. Rap music has the same effect. The difference is that blues achieves this goal through song content while rap does so through total lack of song content. Blues makes you want to die because life sucks. Rap makes you want to die because rap sucks.