And I would be, if I didn't see exactly the chain of logic involved in canceling the flight. If the goal is to establish a permanent human presence in space -- a goal which I agree with, although I'm sure that some of you don't -- then you have to look at the things that will prevent you from achieving that. And number one on that list is: another catastrophic failure of a Shuttle with loss of all hands.
Apparently, the only planned Shuttle mission that doesn't have the delta-V to rendezvous with the ISS in case of tile loss is the Hubble servicing mission. Thus, the only mission where you couldn't use the ISS as a lifeboat and repair station is the Hubble mission. So rather than continue to spend time and effort trying to figure out how to repair a Shuttle in orbit away from the ISS, you can redeploy those efforts to -- for instance -- trying to build a better vehicle to replace the aging Shuttle fleet.
All you have to do is be willing to give up the Hubble Space Telescope sooner than you would have otherwise. It makes perfect sense.
It doesn't mean I have to like it.