Poetry is, in a very real sense, a luxury; to be able to write, you have to have the financial means and the time to do so. If all of your time is dedicated to simply helping your family survive (say by subsistence agriculture), you likely won’t have as much time to craft poems. As America is (despite the recession and very high unemployment) still among the wealthiest nations, it’s no surprise that we have many, many poets. (In this respect, the whole “there are too many poets writing bad work” could fairly be called a first-world problem.)
That point aside, there’s a flip side to the “there are too many writers” argument. If there are too many writers, yes, you’ll have a lot of schlock (most of writing produced will be middling or bad). Nevertheless, if you have a glut of writers, you’ll also, by definition, have an excess of good writing.
-- Brett, at Bark
On the other hand -
There are far too many poets trying to make a name for themselves, to get their work read and loved, and this is likely one of the reasons for the factory-like system of mass-submitting adopted by many younger poets. There’s just too much damn noise, and one way many younger poets combat that noise is to make an ample amount of it themselves, to yell over the din. But ultimately, this only adds to the problem; the supper conversation gets louder and louder until nobody can hear anybody else. How this problem will resolve itself remains to be seen.
--Sean Bishop at VQR
Maybe all this cancels itself out.
Addendum: Ray DiPalma writes in with the following quotation from Yeats:
"I had now met all those who were to make the nineties of the last
century tragic in the history of literature, but as yet we were
all seemingly equal, whether in talent or in luck, and scarce even
personalities to one another. I remember saying one night at the
Cheshire Cheese, when more poets than usual had come, 'None of us
can say who will succeed, or even who has or has not talent. The
only thing certain about us is that we are too many.'"