Since a G update some months back (maybe 8 months) the domain has more importance for defining its results. Recently G seems to have merged plural and no-plural.
For me, in very competitive areas I think it can give you an edge to get number 1.
For my AU credit cards site -
www.creditcardoffers.com.au - In G in AU I am number 1 for credit card, best credit cards, credit cards australia etc, number 2 for term credit cards.
Though a point is that you can get the keyword in subdomain or folder extension and it appears to have a very similar affect. I have seen some
SEO people do this incredibly well.
In the end, content (in page
SEO) and in bound links are the 2 major SERP factors for G.
In closing I always try to get my major key phrase as the domain name if possible.