This is actually a very good idea. Right now, the Astari are purely your adversaries to be destroyed. It would be much more interesting if the player had to weigh the cost of losing trade relations when dropping swamps/meteors on the Astari Village. Of course, the whole happiness meter needs to be better balanced before this idea would work properly.

i guess they could make it where you must have more happiness to trade with them,
or perhaps you could ally with them and therefore have a slightly more permenent trade agreement.