They're cheaper than most fancy purebred designer dogs and dare we say...cuter? And the fact that they can carry loads of up to 100 lbs make them great for touring bands, people who hate carrying their kids on long journeys, etc.
Editorial note: Whoa! You've found a super-old post here on BuzzFeed, from an earlier era of the site. It doesn't really represent where we are anymore, and may in fact be totally broken, but we're leaving it up as a part of our early history.