Obviously it's not ideal to share SSH keys, but lots of teams will share the default EC2 keypair for example. This makes it much easier to pop that key into 1Pass, share it with the team, and easily get everyone into the box.
And, frankly, 1Password gui is much more user-friendly than other SSH agents. Personally, I'll stick with the tried and true OpenSSH agent, but I know many will be attracted by this feature.