I agree, this would be an excellent idea.
Infact, this made me think of somehting, as I really want some improvements in combat to begin with (like control) mayby targetabgle vitals and systems, that way you could disable engines and use salvage craft to steal the ship. Knock power off line, drag it back to a space dock or planet, if the crew won't surrended, easy enough,blow a small hole in it and space them, few turns for a repair and you are golden with a brand new ship. Or leave it at a base and have it reverse engineered to salvage technologies form the newly "appropriated" ship.
Even without this sort of mechanic, a small chance of "researching" a component you can't make would be nice. If their ship had a BHG on it and you haven't researched that yet, there should be a chance of learning the tech from the wreckage.
Likewise, one thing that always bugged me in GC2 was the inability to learn a tech while flipping (or buying) a planet. Nothing worse than flipping a planet from the Korath only to find all their slave canyons got bulldozed because I hadn't bought that tech yet.