Take Pandora for example. I came across the following section on their submission FAQ.
To submit music to Pandora, you'll need these items:
1) a CD of your music
2) a unique UPC code for that CD*
3) this CD to be available through Amazon as a physical CD (and not just as MP3s)**
4) the legal rights to your music
5) a standard free Pandora account, based on a valid email address, that will be associated with this submission
6) MP3 files for two of the songs from your CD
Once you have all of these items ready to go, you can submit your music to Pandora for consideration here: http://submitmusic.pandora.com/.Take notice that the only way to get on their playlist is to have a physical CD for sale.
It's the same thing if you want your music reviewed. It doesn't matter if it's on a blog or traditional media, you're not legit until you have a physical product that you can send to the reviewer. I saw this exact situation for myself a couple of years ago when I was producing the first SNEW album. I was all for releasing it digitally but the band insisted on a CD and they were right. Even though the music was released online months before the CD was available, they couldn't get a single reviewer interested until the physical CD was released. As soon as that shiny plastic disc was available, they were perceived as a viable entity and received more than 100 reviews (almost all of them great, by the way). For their recently released CD, "We Do What We Want," there was no question that it would be available on as many formats as possible, and once again we've been rewarded with at least as many reviews, band interviews, and a ton of airplay. I'm convinced that it wouldn't have had nearly the success without the physical product.
It used to be that pressing CDs was a pain since you had to not only pay for them up front, but keep them in inventory and distribute them as well, but even this isn't much of a problem these days. Services like Kunaki not only allow you to press CDs on demand, but they'll drop ship them as well. They look like a million bucks (as long as your artwork looks that way) so that old worry at the "CD-R look" doesn't apply.
So while there's no doubt that the music world is more digital than ever, the CD is still a useful distribution tool. Ignore it at your own peril.
Check out my Big Picture blog for discussion on common music, engineering and production tips and tricks.