Earlier quoted context omitted.
It seems that you are disregarding the vast majority of Facebook/Google+/whatever users -- who still don't know how to, or don't want to setup their own domain and manage blogging software. Yet, they also want to have a place to put their voice out there. A system like the one that GP proposes, while it could be pretty awesome, would be limited to a very small, extremely homogenous population. It's not hard to see wh…
I would argue that it could be made possible to allow folks to get domains, hosting and software that they control as easily as buying a toy on Amazon. Domains, DNS and hosting setup doesn't need to be hard - it's hard because no one has tried to change it.
Everyone knows what WordPress is, I think people who entertain the idea of publishing are aware of their options now. The draw of social networks is that there is a low friction process -- facilitated by an interested party -- which makes it very easy to go from ideation to publication. Until very recent versions of WP, it was a pain in the ass (from a regular user's perspective) to simply post a set of pictures along with some thoughts.
If we look at your set of questions, something like e.g. Facebook provides answers to all of them which are, yes unsatisfying, but the trade off is a low-effort process.
EDIT: Also, out of curiosity what do you use to host your site, and how/why did you choose it?