If you don't like it, fork it, right? Isn't that the main strength of F/OSS? For example, CentOS is a white-label fork of Red Hat Enterprise Linux. The same argument could be applied to Canonical's inclusion of Adobe Air and Flash in Ubuntu.

Canonical is targeting a market previous unserved by other Linux distros. To get to these users, the experience needs to be polished and complete. There's a reason that, for example, Slackware, isn't going to be installed by your grandmother...it's too difficult.