I believe one of the reasons why we have so few illuvials(orbs) in OW is to combat bots. What if you filled overworld with many more possible encounters but they were mostly t0s in every travel tier.
Not sure what the long term plan is but what if the orbs attacked you (in the future illuvials will attack you)? You had to shoot them till their health was low, only then you were able to engage an encounter. If we had t0 illuvials in every tier of travel then you could have many more obstacles/enemies/engagement. Gotta get through the holds of t0 to mine or to find higher tier illuvials.
Possibly different color orbs or different size orbs could be used to denote higher tier illuvials in that encounter.
Possible quick way to add more life to OW.