Because I some support from atleast a couple of posters in the 'How's the AI thread', I thought I would lay my ideas out clearly for the dev's conscerning the fixing of diplomacy and tactical exploits.
Diplomacy in this game has simple, transparent mechanics. There are diplomacy scores which affect the interaction between 'players'; the player with the higher score is likely to get the better end of the bargain, forcing the second player to act against its own interests. I love the 'gamism' here. The only problem is that the human player is not affected by low scores to nearly the same degree; sure, a player's tactics can be blunted, i.e. they can't get a good tech trade, or incite a war, etc. But they won't be forced into a bad trade or a war they weren't prepared for either. The human is at worst at a stalemate when it comes to diplomacy.
This substantial advantage is further accentuated by the fact that diplomacy, unlike a military, cultural, or technological route to victory, has no real maintanance; just a series of techs, a mutually beneficial trade agreements, and some nominal give away every once in a while; diplomacy modifiers rarely see a truly substancial drop due to in game behavior.
Further, the military and diplomatic paths are all to often complementary, i.e. the use of alliances as a defensive shield until a player is ready to stab said ally in the back, the attempt to maintain peace up until a quick planet strike can be arranged, or manipulating an AI into a declaration of a war it can't fight so that it is both tactically on poor ground and subject to negative diplomacy modifiers. Given the player's already significant tactical superiority, it doesn't really make sense for diplomacy and tactics, two areas where the human excels, to be this complementary. The following suggestions are meant to decouple them somewhat and allow for the possibility of a major downward swing in a diplomacy mod given reasonable player choices; i.e. a more interesting tradeoff.
1) The succesful implementation of a first strike war, i.e. taking one or more key planets from another player within a couple of weeks of a war declaration results in a major diplomatic penalty. The first striker would not have to be the one to declare war to recieve this penalty; it is determined by actual war results. This will make it more likely that the player will be at war with one or more other civilizaitons before it can prepare another planet rush, meaning it won't be able to peacfully get its ships in position. Because a first strike would have already have been carried out, this rewards the hardcore player with greater challenge without overwhelming the newbie with cumbersome new gameplay mechanics; it also helps to avoid false positives that could come with trying to hard to get the AI to preemptivly counter such tactics.
2) Diplomatic and moral penalties for breaking alliances and treaties; recognizing that positive diplomatic modifiers are one of the intended benefits to come from these options, it would make sense to, instead of eliminating such modifiers (and thus create the possibility that an AI would attack and ally, making the alliance practically meaningless), it makes more sense to punish specifically exploitive behavior. So breaking an alliance and economic/research treaty with another player will create a negative diplomatic and (temporary) morale penalty for cumulativly for each alliance/treaty broken. This will encouarge picking such a partner for the longhall, i.e. based on defensive and economic reasons as oppossed to as a short term tactic.
Anyway, its late, and thats all I could think of for now. I invite anyone with similar suggestions or criticisms (especially the devs) to post in this thread. Thanks for putting up with the rambling.