WOW...!
I don't envy them one little bit...

...!
I'd rather get a return ticket for a 'bus into town and back again...

...!
Paul..."Sainsbury's Supermarket, please..."...

...!
To each his own... I'd love to go, despite the risk (current odds of not coming home are about 100 to 1, I believe).
And I'm not worried for them: the only other major failure on an Orbiter was the SRB thing that brought down Challenger, and they've got that under control. Even if a chunk of foam damages the orbiter in similar fashion to Columbia, they are planning an orbital inspection of the bird on this mission, and the astronauts will have the luxury of saying"no thanks; we'll hang out on the ISS for a couple months until you can get another orbiter up here". I'm pretty sure they even have a plan for trying out some repair on damaged tiles while in orbit... Bondo and duct tape, I think...

A long way from playing 3-D chess in the cafeteria under artificial gravity while hyper-lighting off to distant stars while protected from radiation, but it's a teeny step in the right direction.

Prior to having ISS, crews with such a problem were just plain screwed.
If they do have to wait for another ship, and
that one has a problem... well, I reckon the Russians can help out, or maybe Burt Rutan can put something together.
I'm pretty excited about this mission: even while being phased out after some tragic system failures, these machines are helping lay down some important stepping-stones. Can't wait to watch the EVAs on this mission; should be very interesting.