@seafireliv : Cool idea, and I'm all for having to spend research time to speak to any given race, its neat, though, perhaps enabled if one or the other party spends the time.
In general, my issue is that the current system is a system of barter, and an absolutist one, and the only choice you really have to make are research choices. This notably, makes diplomatic victory another version of research victory, and not a fully unique victory type. That is okay it doesn't need to be completely unique, but it is way too heavily linked to research only, at the moment.
My choices, should be both tech, planet developments, and player input/actions. For example a Tech could be "Spiritual Respect" giving me a distinct boost for races with the Spiritual trait, despite being of a different ideology choice. That bonus, shouldn't be 'automatic' though it should enhance the boost I get when I do something for the AI, such as give them a gift.
For example:
Without tech, gift giving grants me +3 relationship points from the race. With that tech, the gift gives +5. Or some such, and modified by other factors such as ideology choice. not just an automatic +1 or +1 per turn to ALL races.
Right now, you choose to do Diplomacy Tech or NOT, and the fact that these bonuses apply to all races is huge. I don't ever to DO anything to make everyone like me, I've never had to give the AI a gift, and he doesn't begrudge me for making EVERY deal perfect trades for ME. I get the right techs, spam embassies, and I can be as genocidal a warlord as much as I like and everyone will love me again within 30 turns, easy.
Naselus has quite rightly pointed out, that the system's values could be adjusted to reduce the absurdity, for example, making Embassies a wonder (they are +X per turn, on a 10 point scale). The scale system alone would improve things, if increased to 20 or 100.
But this still doesn't link diplomacy to player actions.
Why should it be linked to player action? Well I don't have a objective answer to that. Something feels wrong about simply "spending" (directly through trade or by research/planetary structures) to create good will. Real diplomacy and real history is always deeper than that, and I think player's need more interesting choices than "do I need to get new treaty options and diplomacy bonuses, or better lasers right now?".
I'm not precluding the role of techs, but they currently have a super-power status in the equation, when that should really be the place of player actions, such as wars, gifts, respecting borders, and general attitudes in trade (how much you nickle/dime the AI in a trade should give a small bonus or penalty).
Many of us really don't like what is a basic feature in many games, being "teched". For another example, look at military subsidies project, tech locking that did not help anyone wean off of the infamous econ wheel (per planet).
My 2 cents. Thanks for reading.