civ2civ3: AIs Should Never Give Away a Hard Embassy Without Receiving One.
I agree about Hard Embassy. I think it was that way in previous versions.
About "shared vision", I think AI sees the whole map all the time, I guess it is not that important for them.
Edit: note I can't change this behaviour in the ruleset, it would require editing AI code that I don't know.
I also think that in classic, AIs shouldn't give away embassies ('specially to human players) to allies, without getting one in return. I can't think of a technical reason; it just seems wrong/inconsistent.
With tech-leakage in civ2civ3, AIs should never give a hard (non-Marco Polos) embassy to an ally without receiving one in return.
I also think that AI allies shouldn't give shared vision to a human player, without getting it in return. The AIs do give shared vision to each other, while sometimes not receiving it, and I think that's OK. But they shouldn't do it to humans.