I'm not sure what difficulty you play on, but on Obscene, it isn't that easy to make trades for things like that. Usually their research is so ahead of mine is some areas, it limits what I can trade to them. Also, to stay ahead militarily, I rarely have a lot of cash on hand until perhaps mid game, so it's difficult to trade large sums of dough for techs/planets or to make war. With some races it's easier (drath, terrans), but usually it's fairly expensive.
I play on sucidal, with custom yor (only +40 diplo at creation) -not exactly the best diplomats around . Strat is very easy - translators, and then research technologies which are +diplo and those which you can get good trades for. Build galactic bazaar and then game is done.
Some races are harder to trade with than the others (iconian,drath and humans) but it is still doable. Heck I traded all their treaties for a bunch of techs .
Disabling tech-trade is NOT a solution. All 4X games have tech trading (since Civilization I) and without it, game loses a good deal of its appeal
Exactly. Might as well remove diplo altogether if going this way
The other weak AI spot is trading high-quality planets. For a few techs, AI is willing to sell PQ>20 planets, just because they are temporarily underpopulated and non-developed. Such planets have the potential to become AI's main strongpoints in 20-30 turns, but obviously AI is not programmed to take that into trading calculations.
And on the other hand AI wont trade high pop planet even if I offer everything I have and surrender on top of that! The trading values and algorithms should be rebalanced. Planets should be tradeable - but mostly for other planets only (or for A LOT of techs, cash and ships). Same with ships and starbases -you should be able to trade them if you offer similar things in return.
Tech for tech trading is generally fine (albeit I think AI overvalues some and undervalues other techs- unique techs should be a lot more valuable, while the planetary invasion , warp drive and such should be more tradeable) .
Also anyone ever able to trade for influence? - Was always a completely broken option since original game and trough 3 expansions.