It's amazing how often product decisions head this way for the purposes of 'removing friction'.
In security, friction is a GOOD thing. You want to have some ceremony to do things. It's pretty much inevitable that people will give up control for convenience.
Look at Artifacts for example.
It's an inherent tension, and is also why so many things are insecure. People hate friction, and so they don't use secure stuff and turn security features off. Security abominations like "curl | bash" and package managers that traverse trees and download stuff and run scripts are popular for a reason.
It's true in the real world too which is why even in secure buildings a person can often slip in by coat-tailing someone. Stopping every single person to check ID is cumbersome and slows everyone down. People have stuff to do.
Truly high security environments are zero-tolerance, which makes them annoying and expensive to work in. I've talked to people who have worked in US military and CIA/NSA places and a very meaningful amount of time is spent complying with security and jumping through hoops. Even with all that, stuff gets leaked and stolen.
Which is in turn why for convenience, security is a bad thing, making people who do not think about threat models in their sleep opt out.
Problem is striking the right balance, and auto-forwarding your agent to foreign machines is not the right balance. At least not without being able to filter and approve individual signing requests.