Extra idle animations seems kind of minor, but I could get behind it. On the other hand, in terms of random untargetable critters and things, that also sounds like it would make the game so much more alive, but it would have one slight drawback. You'd have to render these things, and while I doubt either PS4 or high-end computers will have much of a problem, players who are stuck playing on a normal computer set-up will probably be forced to reduce their settings even further, and PS3 probably wouldn't even get the option to see the additional wildlife (Though that would be awesome incentive for those still on the PS3 version of the game to upgrade).

I'd hope that these additional wildlife, if implemented, would have their own toggle so that players on the low-end performance wise don't have to suffer extra lag. This would of course mean that these critters would be purely aesthetic (which should be their only intention when adding background wildlife) and cannot be targetable.