Yes. I think we should actually have more dynamic sites and this already happens in both games. There are certain sections of the map where machine spawns and its not marked on the map by a SITE icon. If you fly over and and over, different machines appear.
For example, there is a place in the mountains where you fight a Frostclaw with a young Sky Tenakth trying to prove themselves. If you return here after the quest you can find Sunwings and Burrowers, or a Scorcher and Frostclaws, or Bellowbacks, or Lancehorns, or Firehorns. Even in some icon SITEs the amount vary, there is one of the Frostclaw icons where you can find one or two Frostclaws, Fire clawstriders, Shellwalkers, etc.
The only problem I see with this is the resource hunting, but if the resource for key materials was reduced (seriously, I must have stripped hundreds of tremortusk's tusks) this might not matter that much. Another problem is testing as well, more testing and development would have to be done so that the machines and terrain work properly.