Comes down to personal preference. I personally like a minimalistic look. I don't want a huge rack full of home entertainment gear sitting in my loungeroom. I want a small, inconspicuous box that does so much more than a DVD player. Particularly in a small appartment you want a box that is able to not only play DVDs, but also handle your music, record TV, give you weather updates, present an EPG, etc.
For me, that's the greatest thing about a HTPC: a DVD player is a one trick box, all it does is play DVDs. A HTPC has much greater upgradability and functionality. As such, it also has greater longevity.