The buttons suck - we knew that a lot of users hated them (it adds 4 * 20 additional HTTP requests to the main page), but they were worth too much traffic to do away with. Social network referrals likely surpass search engine referrals for a lot of blogs and web sites. They have steadily become an important web traffic navigator.
If somebody can figure out how to make those share buttons prettier and more efficient there is probably a product in that. I would guess that most blogs would love to drop the grid of share buttons that can be found on every post.
Otherwise I totally agree with not going for subdomains. We setup each property on a separate domain and initially had some on subdomains. The subdomains didn't rank at all and didn't help our PR or SEO. As soon as we switched each property to a separate domain our search referrals rocketed. For eg. you can now find a crunchbase link within the first 5 results for the name of a startup, while similar records for posts that lived on subdomains wouldn't rank at all. We had around a dozen different domains and frequently linked between them (for eg. each post would have multiple crunchbase links), and it worked really well for search ranking (search engines are ~40% of crunchbase traffic, IIRC) It shouldn't be like that, but it is.