I tend to agree. Until CACert becomes more mainstream, it is not as useful, except within a community of users who also use it.
The main advantage I'd see with CACert is wildcard certificates (which you dont get at the first level with startssl). Yes you can generate/maintain your own, but maintaining a PKI rapidly becomes a pain.
With CACert certs, it can be as simple as "sudo apt-get install ca-certificates" to get CACert support (for instance, to validate CACerts used in server to server SSL connections).
http://packages.debian.org/wheezy/all/ca-certificates/fileli...