Steve takes things like personal responsibility and respect seriously. Tony's got people he pays to take care of that kind of thing, and anyway, he's pretty sure that he's going to die of some exotic disease in his workshop, because Dummy's still a little spotty about what is 'clean' enough to put on an open wound.
The rest of the Avengers are in this for gain, except for Clint, he just enjoys being a dick.
Tony Stark has once again engineered something that might well lead to the downfall of Western Civilization. No one's really surprised. This time, however, it might just be the lesser of two evils. Clint and Phil hate playing pickup, but damn, Clint loves the Roombas, and damn, Phil loves Clint, though he's not really sure why sometimes. There are four reasons for kidnapping Tony Stark. Tony's sick of all of them.