Publishing poetry by major houses seems to be largely a matter of prestige and awards. Most collections of poetry, I suspect, don't make the publisher a lot of money. A few "house poets" manage to sell pretty well on a consistent basis. Mary Oliver is one, as is Billy Collins, and I guess Ashbery was another.
Here's a link to the current Norton poetry list. For obvious reasons, the anthologies take prominence:
http://books.wwnorton.com/books/subj... aram=SortDate
I should add that there are quite a few books I've enjoyed on this list and that I post it for informational purposes only.