I've never seen aliens give each other their unique technology, what are you talking about?
Two responses to that one.
First, it sounds like a bug bordering on an outright exploit to enable tech trading when the AI is that pathetically unable to use it properly.
Second, some tech trees are defined as much by their weaknesses as by their strengths. The Yor with spammable econ buildings play like a completely different race. More on subject, the Arceans with advanced engine techs are a completely different animal from the Arceans without.
This leaves out issues with the techs the AI will trade - unless something has changed dramatically, the AI will still trade any non-unique tech with other AI's like it was baseball cards, while only parting with their own techs to a player for an arm, a leg, both eyes, a kidney, two thirds of your liver, a marrow transplant, a couple of yards of intestines, three units of blood, and your firstborn son.
[edit] In any case, this is all beside the point. I'm hardly alone in leaving tech trading turned off. I'm not even alone in doing so to preserve the unique nature of tech trees. It is fallacious to say or imply that a problem that can be solved by tech trading doesn't need to be addressed or isn't real. Many people have major issues with tech trading in the game, enough so that there is an official option to turn it off because of the widespread perception that it was just plain broken. If there are tech trees with holes so gapingly huge that the require tech trading be enabled to work properly, that's an issue worth addressing.
