by snowfake
What I think might be a good solution is to make the systems with portal more valuable to offset the innate risk that comes with revealing first warp portal that comes into play.This can be done by adding a prebuilt orbital (or two - might be an overkill though) in the system.
This way even a player going for a turtle strategy may find the system worth keeping instead of just instant discarding (as was the case in all my games so far).