Re: why aren't they going to the ISS?
I guess one reason might be the ISS was started 23 years ago with a 30-year lifespan, with individual modules having a 15-year one. So it's already past its date, even if said date keep being postponed. The Russians themselves don't seem very keen on keeping it running.
Also, with their current domestic politics aimed at China, I really doubt the US would extend an invitation.