My straightforward answer: because a bunch of my Facebook friends seem to be looking forward to moving to Diaspora and I doubt any of them has heard of Appleseed.

It's possible that in a couple of months Diaspora will look a lot less like a Great White Hope. We will see.

When I said "Diaspora, not Appleseed", that was meant as clarification of intent and not as a refusal to host Appleseed instances.

That said, I'll only use Diaspora for myself, but that's based on personal preference.

I know Ruby like the back of my hand and am comfortable with Rails. Also, my site's built in Rails, so Diaspora will probably integrate nicely.