Both. Reduce waste and pollution for obvious reasons, but it also reduces emissions from the creation of virgin plastics.
Plastics and petchems are a major money maker for the oil and gas industry. By reducing the demand for virgin plastics we take another small step towards making the oil and gas industry rethink their plans for more drilling, burning, polluting etc.
If we want a clean future we need a better way to make plastic. Be that from improving the currently pretty poor recycling process, and/or find new feedstock.
Princess films do dominate but the male characters can be highlighted too,