The EU has ruined plastic water bottles
spectator.co.uk
spectator.co.uk
This would be amazing but there is a possibility that it's actually impossible. There is nothing magical about the environment. Paper and cardboard are physically degraded by moisture and chemically by fungus. The reason plastics are popular is because they don't do that. The more degradable you make a plastic in the environment, the less desirable it's properties are for foodstuffs.
I prefer the new caps, it's more convenient to manage one object than two.
IMO real problem with caps is that this was not invented by VC backed startup, which makes it ideological challenge to some people.