In this game, never say never.
Indeed. There are certain situations where one might potentially gain advantage by selling/trading/giving away one of these goods. If I were going for a diplomatic type victory, I might gift a tech, if I thought that this action would bring me close to another race. If I were going for a research victory, I might send a tech along, if it would keep me out of a conflict long enough to finish up the final tech or two and win that way. If I were trying for an influence victory, oh, I don't know... maybe more bc to put towards another influence starbase. So, you're right- never say never.
But no matter how I start out my games, they almost always end up the same way- head to head. Let's take your current game, for example. What happens when the Korath are gone? You'll be facing the race that you have given that tech to, and will have lost your advantage in that respect. In other words, the time that it took to research that tech will have been wasted. These are weeks of research time that could be spent on miniaturization, in order to be able to squeeze one more weapon onto your ships, or on logistics, to give the advantage in fleet size, or any number of things that might actually help you defeat your enemy.
I have found, in my own experience, that these goods are only valuable if I keep them in my pocket, so to speak, and doing otherwise inevitably comes back to bite me in the backside.