Using the keywords and key phrases in the domain names are given importance by search engines whether used with or without hyphenation / dash.
Previously search engines where not very smart and hyphenation was important, but now it can be avoided and the search engines can figure out the key phrases in the domain names without using dash.
The use of keywords in the domain name is also good as people can easily link to your website using domain name and without their knowing, they will be adding your keywords from their out-going links which we also call the anchor text.