Bad things about Proof of Work mining:
- Miners push the price of tokens down because they sell to pay electricity
- Miners pool their resources together and create cartels that foment centralization
- Graphic card prices increase
- Then environment is severely polluted!
I think POS will definitely be the main system in the near future. It's ok the POW is currently using a surplus of energy, but crypto world can't grow at current level and get a mass adoption only considering such kind of terrible energy consumption.