Different populations could get angry at all kinds of things: Destroying uninhabitted planets could be considered an environmental atrocity by some people, as could the use of terraforming facilities.
Also, the issue of how much a given population knows about current affairs in the galaxy raises huge questions about the whole "fog or war" thing in SEIV. If a neighbouring empire has a major planet glassed, don't you think news would find its way to me sooner or later? Refugees, traders, reporters, travellers etc would be bound to spread information regardless of political boundaries, but unless you have a partnership treaty or a ship in the vicinity there is no way to know.
Of course the reason for this is that it would be hideously complicated to code, because then you get into issues of how long it takes gossip to travel from system to system, whether or not news would filter out from events with no survivors, whether or not news would travel across war-zones or not, whether or not novae should be visible years later by normal-light travel etc etc etc etc...
BTW, welcome Alari. Lookin' kinda furry over there
