Indeed, desktops are kind of boring if your primary goal is something that involves mobility as the primary focus. But if you want speed? DESKTOP. It doesn't matter how powerful of a laptop there is out there, a desktop will do it faster and for a lot less money. I put together a STUPIDLY AWESOME system spec for a friend - Core i7 Sandy Bridge CPU, 8 GB RAM, 120 GB SSD, 1 TB HD, nice GPU, case, power supply, etc. all for around $1000. A $1000 laptop wouldn't give you half that performance.
And I personally love my desktops because I can upgrade them, improve them, etc. I get that most people don't want to do that, but I do.
I have a soft spot in my heart for the HP Slimline computers - I have two of them in my house - so I'm glad HP continues to develop them...though I think they could get even smaller and quieter and I wonder why HP doesn't want to go down that road.