I don't think this is really as settled or clear as you're making out.
The cold or cool fire you're talking about just means they burn every year, there's less fuel load so the fire burns out before larger trees have time to burn.
Traditionally they weren't doing this out of care for the land, it just makes hunting far easier - kangaroos like to eat the new shoots after a fire, and it's easier to chase / throw things at them if there's thinner underbrush.
Land management organisations have been making informed decisions about controlled burns since forever. They consider all the factors, like fuel load, weather, risks to property, and input from community groups including indigenous Australians.
It's controversial because these controlled burns often become uncontrolled fires.
Things have changed since this type of land management was a thing. Notably people have houses now which they prefer not to be burned down.
Finally:
many plants have evolved to require fire as part of their life cycle.
This is confirmation bias. What happened to the plant species that were vulnerable to fire?