I don't know if this even exists in the original GC2 so pardon if I posted this in DA erroniously.
The plague cure event leaves something to be desired if you're playing the good guy. I got this event and researched it, gave it to everyone free. Their attitude seemed to improve only if I had relatively poor relations with them to begin with and not by a ton then. These people are dying out and I am their savior, yet their thanks seems minimal. They also weren't willing to trade that much for it. It just seemed like a relatively low-key tech to them.
To make matters worse, the Terrans were "friendly" to me, and I gave them the cure. They remained friendly. About five turns later, they suddenly declared war on me. The Terrans had consistently been one of the people I had best relations with the whole game until around this point.