Scouts are needed. Just not when the fighting starts. They're very useful in random map games so you don't waste initial movements to get to a crap planet.
It's not necessary to make them useful throguh the whole game, whiich is what the mine detection is an attempt to do. Instead scouts should be recognized as playing a minor role. There are a few uses later (eg the vasari cloack ability is nice).
Realistically mine detection should be a fairly common ability on ships, probably universal, or at least purchasable on capital ships. They would still play a delaying role as ships burn through them, and frigates would be more endangered. (I think the Flak Frigate should get mine detection, it's already playign a defensive role, let us research that ability for Flakkers.