Compared to WordPress, you definitely do; but think about it, there's lots of stuff in WordPress that a blogger doesn't need. WordPress is not just a blogging platform [anymore]. However, on the other hand, by using static sites you're entering a whole new level of security. But don't fear, for commenting, there's Disqus which is pretty good, and I think it's built into specter as well! Even if not so, adding it is just copying and pasting a couple of lines of code :)

Nah, just use Disqus for your comments. Octopress includes this by default, probably others as well.

I've been using static blogging for about a year now, it's great. Fast, simple, miss nothing from Blogger or Posterous, don't know about Wordpress never used it, and all your content is stored in your own Github repository.

Commenting is a pretty big part of the blogging community. I'd hope it would be included in any blogging platform. But then again there are outside sources like disqus for comments so you can bolt that onto your posts if you feel inclined.