I admit this wouldn't be the most widely used functionality, you'd have to be fighting an enemy of an equal tech level and possibly the same preferred weapon type as yourself in order to make full use of it, but when you do happen upon such a foe, it feels weird to be unable to utilize his captured/salvaged equipment, potentially saving 10-20% on ship construction time/resources, except by adding it to a brand new class which would cause a ton of headache during firing assignments, and especially when the time for ship upgrades and refits comes, not to mention problems with shipyard commonality. A minor conversion tax to account for superficial differences between equally capable components designed by different races, such as weapon mounts or controls, makes more sense to me, but ignoring such minor aspects and accounting for them with an appropriate conversion message upon salvaging the component would work fine as well, as long as the same message is sent upon scrapping a captured alien ship in a shipyard (which is how I actually acquired most of such components in my playthrough).
Being able to research alien components could be useful in general, but it does not fully solve this problem. If you already had a ship with an equivalent component in service, you'll still end up with two different but functionally identical classes of ships, one with a native component and one with an adopted alien one.