Yep, a few glaring omissions, Alice Cooper, CCR, The Clash etc.... but there are perhaps too many different types of band in that list for it to make much sense... There's many great bands there that I don't consider "rock" as such, e.g. Steely Dan and Fleetwood Mac. I think Rush are as good as it gets in terms of a rock band, but their music is quite a mixture. Yes, Floyd and Genesis have the skill and the creativity, but perhaps not the rock ethos to go with it.
The Who, Queen, Zeppelin and The Stones are all prolific, true rock bands who all deserve a vote or two, but for me the epitome of rock and perhaps the most influential in the genre from the outset would have to be Black Sabbath...