I just spend $9 renewing with Comodo's "PositiveSSL" because Let's Encrypt was too much hassle.
This is true. It probably took me somewhere around 20 hours to get everything streamlined with Let's Encrypt (I started before public beta, so the available software was buggy, convoluted, and not well documented). Just like with open-source operating systems, the advantage is not in the initial setup but in how many units can then be deployed for minimal unit cost. If you have only a couple of domains to be encrypted, LE is not worth it currently.
Perhaps the commercial providers should focus on the small-scale users, which is exactly what they probably would rather not do.
This could happen, but I would think some of the cram-all-you-can hosting providers would not want to "waste" CPU power like that. SSL takes slightly more CPU to serve. My guess is the better half will probably do it, at least until browsers start complaining when a site fails to use SSL.