I guess this is what the thread here is about... What are the Biters doing all day long?
Currently they pretty much only complain about pollution by attacking your base and that's about it. If you reduce your pollution cloud then not even that is happening.
I think what kiba wants is that the Biters themselves engage more openly in the resource battle/conflict. To begin with I find a whole logistic system for the biters way too calculation intensive... BUT:
For example they could enjoy building their biter nests ontop of resource patches. And depending on the resource type the spawner sits on top it spawns enemies which have different strengths/weaknesses according to the resource type (for example on Iron Patches the Biters/Spiters have a thick Iron-like armor, on Coal they are more like Carbon Fibre or something, etc). The nests could also drop different "alien eggs" accordingly. That alone would make the biters already more interesting.
But on top of that if you don't kill the spawners off the spawners will take a few resources from the resource patch (acting like a mining drill) with every wave of respawned Biters/Spitters. So eventually you have to clear out the nest or otherwise you might have nothing left to mine.
That would introduce another layer of challenge... a race not only against the evolution factor which is depending on pollution, but also in terms of resource conflict since every generation of respawned enemies will drain more resources from the resource patch until nothing is left.
Of course when the Biters look for new spots to build new nests they will look out for new resource patches with no nests on them.
One could take this even a step further... If no resource patches are left in vicinity they will build a nest in the middle of nowhere... and with that they could spawn new resource patches UNDERNEATH the spawners... so basically they "uncover" new resource patches that were hidden underneath the surface, generating/spawning new resource patches in the process.
That would be even more funny... because then you have to decide how big you let a nest grow before killing the nest to harvest the resources or otherwise they might drain the resource patches with their biter waves before you get to mine them.
On the other hand that would also mean you have to let biters be somewhere around your map to let them find/uncover new resource patches (since they are natural talents in uncovering new hidden resources)... which means a real symbiosis. If you kill them all then you only make life harder for yourself because then you have to expand to the edge of the map to uncover new biter nests/resource patches yourself.
So basically this would allow the huge wasteland you leave behind to be resettled with resources eventually, if you are willing to deal with the increasing biter threat again.