Evan Williams, the co-founder of Twitter and Blogger, argues for 5 Reasons Domains Are Getting Less Important. I think he has good points, but less important still doesn't mean unimportant.
I think a lot of the times when companies opt for imperfect .com domain names (or ignore .com altogether) has something to do with the increasing saturation of major TLDs. It's simply harder to get a perfect domain name nowadays.
What do you think?