clarry: Well respawning isn't a problem, but is it so much effort to not make it happen in an immersion-breaking way if you happen to be near a border?
Yeah there probably could have been better ways to handle it, like respawning after certain amount of time etc.
Anyway, my theory is that it is done that way because of the console versions of Far Cry 2. I'd think it takes much less memory and effort to just "reset" a map (all the enemies, items etc. in it) when you re-enter the map, rather than e.g. trying to keep track of each and every killable/destroyable/pickable item in the whole gameplay world and when it should be respawned. They chose the easiest way for respawn.
Maybe I didn't find the respawning that big a problem because I didn't constantly zig zag back and forth between map borders. I usually went from location A to B for some mission objective, and then maybe came back from B to A. At this later trip I'd then encounter respawn enemies and items, but it would normally be quite a bit later, after I had completed the needed objective at B.
But if you want to freely roam in the area without caring about objectives and then to go back and forth, then yeah I guess it could feel problematic. However, while enemies respawn, so do any useful items too in the same area (ammo, health kits etc.). So sometimes I might even want to trigger respawn in order to get more health and ammo.
