No users should be excluded from the Web, even if they have no idea what they are doing. Still, I am almost certain that any user who wants a good experience on the internet is going to upgrade to a more recent version that supports Web standards.
With this fact in mind, it is safe to assume that any user using IE6 out of choice will not care about the visual experience they have on a website, as long as they can use it to get to the information they require.
This theory can be applied to any individual, organisation or company, pretty much across the board. Why punish the many to please the few.