Why is the straw inherently a problem though? If properly exposed of, there's no issue with them. People who are buying expensive metal straws wouldn't just throw them out in nature anyway, so I'm not seeing how those things solve any problems. Sure, a ban, like you mentioned would keep assholes from littering, so that would help independently.
Edit: Did some googling, and this article sums up my concern nicely:
"Banning straws may confer 'moral license' – allowing companies and their customers to feel they have done their part. The crucial challenge is to ensure that these bans are just a first step."
Any single-use non-degradable object is an issue. It's not as much about throwing individual straws out in nature, but loads of bars/restaurants/cafes, each throwing out hundreds of them a day, every day. Next, we can grab another single-use plastic thing...
Edit: Did some googling, and this article sums up my concern nicely:
"Banning straws may confer 'moral license' – allowing companies and their customers to feel they have done their part. The crucial challenge is to ensure that these bans are just a first step."
https://earth.stanford.edu/news/do-plastic-straws-really-mak...