Totally agree.
I want a more immersive conversation system (with a chance of failure) similar to something you might see in a Fallout or Skyrim game personally... but regardless, the current barter system is really easily manipulated and the whole "per turn" aspect of diplomacy factors isn't easy to see/measure as the player. Then, the buildings providing a direct bonus to ALL relationships is huge, not to mention the general bonuses/etc.
Where as a more simply stockpile/point system might actually work better.
For example:
Base relationship with a player of a opposing ideology = 0, same ideology = 20.
Every war you launch against another player of different ideology than the relationship partner? -10, same? -20. Do they like that person or hate that person? +/-10 in addition.
Every war you launch against the relationship partner? -50
Every planet you take? -points = % of empire relationship partner empire (they have two planets and you took one? -50 points).
Every gift you give? +2, every trade at "fair" value? -2, every trade at "Good" value 0, every trade at "excellent! its almost a gift!" +2
A single wonder Embassy? +1 every other turn?
Every trade route, +1 every other turn?
Go to war for this relationship partner when asked? +35
Point is, most of these are static, they can have different values based on the ideologies, and perhaps on the personality traits of the race, and basically, most things will make people hate you, but continuous trade, trade routes, and avoiding warring too often will get you in good standing. Treaties/etc. could eliminate some of the penalties for example.
Its a 2 bit system I cooked up in 3 minutes, but it basically uses the same systems GC3 has now. I just applied a little logic based on Naselus' incredibly valid point, that the whole system needs more room to work, 1-10 just isn't enough for values, 1-100 would give a lot more freedom for balancing this stuff a bit.