What I think is good about it:
- It dynamically alters the enemy to your progress (more progress, bigger factory = more pollution, higher evolution)
- It opens up interactions, so you can take precautions to reduce pollution in order to reduce the negative effects of it
- It also has a nice aesthetic, because factories do pollute in real life as well
- Desert/Taiga Maps are considerably harder than Forest maps (you get attacked A LOT more and evolution rises much faster)
- Pollution controlling enemy attacks makes for very weird attack patterns
- It also causes you to suddenly not get attacked anymore when you start using efficiency modules
- You cannot affect pollution in a meaningful way early/mid game which robs the player of most interactions with it
The reason why I think this has no or nearly no negative side-effects is because there is just two types of games I had so far. Either there was a large forest and I didn't get attacked at all, so in that case I could have used peaceful mode instead or I was in a less green map with small starting area and got attacked constantly anyway (so there would not be much of a change, except maybe smoothing out the attacks, which would be positive).
The next reason is because you have so little control over your pollution until late-game. If there was meaningful interaction with the mechanic I would see merit in the idea of pollution-based attacks, but you cannot really control it. All you can do is play on a desert map for more attacks or a forest map for no or nearly no attacks. What and how you build has nearly no influence at all.