I actually would agree with this. No nation in real life wants to acknowledge that they were responsible for causing horrible world events such as the persecution of a culture or religion, be found out for espionage in another country, or responsible for devastating wars that surged across their continent or took place overseas, especially if it involved (a) annexation of hostile territory (think Germany's annexation of Alsace-Lorraine causing France's great feud lasting into WWI), (b) creating puppet states (Vichy France, WWII), or (c) burning down cities/salting the earth type tactics (almost anywhere in history) causes resentment. While I do agree with the city "borders are too close" issue, your AI friends generally won't give a **** if you take the city that was just settled next to you unless you really had no casus belli or you are a backstabber. Likewise, if you do get the signal from an AI that you should move troops away from your borders, remember: historical context teaches us that most mass mobilizations of troops towards a border of a foreign country is cause enough for alarm as either a prelude to an offensive for war or purposely mobilizing a defensive force in forethought that someone else is threatening one's borders. In this case, if the AI is really plotting against you, notice that they will probably not ask you about your intentions, especially because the AI might perceive that (a) player knows that I will make an attack and/or also (b) the units at the border are primarily within player's own territory near my borders.
Essentially, I am not asking people to completely re-think the Civilization V AI diplomacy as intelligent, but simply as programmed according to historical conventions, knowledge and AI "personalities".
EDIT: Oh, and do I hope for SMAC-like diplomacy? Yes, of course I would! The question of whether that would be implemented, however, is now a bit more obvious. I am simply hoping that the diplomatic penalties will be altered to cater to the fact that this is something a bit more than civ in space. Just a warning: if you are in a cold war with AI, expect there to be diplomatic penalties if you steal their colony out from under them. The only case where the AI might consider this rational is if the colony is insanely close to your base, and even then it might still give you the diplomatic penalty unless it is afraid and unwilling to question your authority. They also may care if you raid their stations or steal them out from under them. Expect the same or more warmonger penalties to be added for attacking another colony without a very good reason such as "they started it!" or if you have the appropriate friends to back you up in supporting your cause. Differing affinities will also force conflicts, if only for the fact that the affinities may head to polar extremes.