I think it would be nice if we had the option to very slightly restrict where we could travel to places we have already been.

Perhaps require either a Silo, a Planet Hopper, or a Cargo Bay on the surface? I'm not sure what the exact best constraint is.

The issue (as I see it) is that right now, you can use a Hopper for your first journey to a planet, which does not feel in the spirit of the mod to me.

This can of course be an optional setting.

I agree with this remark. As a convenience mod, a setting to enable travel to freshly generated planets should be an optional setting, enabled by default. It will be added soon.

Implemented in 4.1.0, on by default.

Impressive turn around!

Thank you very much.

The Factorians on my server have suggested to limit the hopper to only be able to go to planets that connect with the one it's placed on.

Making it more in line with a "hopper" and not a "start to finish"