I think in this day, it would be silly for most authors to overlook the connections they can make with online networking. If you are writing for a niche you're already well established in, then you can probably forgo the online media craziness. But for most everyone else, I think it's close to necessary.
It doesn't have to be time consuming. Set limits, goals, etc and stick to them. For example, set a goal to spend no more than one hour dedicated strictly to email. You may need to alter it as your needs change, or make additions as you discover new networks. I've been completely enraptured with Ning the last few days. Now I have to set a limit for myself and stick to it (hopefully lol). There's just so much to read :)
I agree with Rainy. I think authors are missing a great opportunity to meet fellow authors as well as readers. With publishers trimming their marketing money and social networking growing, social media is not a thing to be ignored.
Like anything, you need balance. It doesn't have to be time consuming. If an author was doing a booksigning, they'd sit there for a few hours. But social networking doesn't have to zap three hours of your time in one shot. You can do a little at a time. :)
Social Media is a must for authors wanting to get their name out there. The more interactive you are on sites like Facebook and Twitter, the more potential readers you are making contact with. I think that it's important to build that relationship with readers