Purpose of "immune response" node?

Immune Response
Blight encounters in your maps spawn 50% more non-unique monsters.
Blight monsters in your maps spawn 100% faster.

What is the upside to this? Does it give you more rewards? Is this information available somewhere? (Could not find info on the wiki)

The upside is, well, 50% more non-unique monsters. More monsters, more loot, more exp.
It would also mean longer encounters, but "spawn 100% faster" compensate for this. Kind of.

if you can clear the mobs without risk of failing the encounter, this just gives you that much more juice.

more mobs == more map loot (currency, div cards, exp)