Canonical are currently positioning themselves as champions of the "selective tinkering" concept in the Linux desktop distro space. They do this primarily by explicitly tolerating proprietary components in cases where they believe doing so leads to a better end user experience, as well as by tightly controlling the UX design of the default Unity desktop.
They're not the first ones to try this (Lindows/Linspire are the most obvious predecessor), but they've done an excellent job of building a community around their product, which is a big factor in Ubuntu's current popularity.
It's still an open question whether this popularity can be translated into market penetration and popularity, but the rise of software-as-a-service computing certainly gives them a fighting chance.