Proprietary batteries are useful for getting the best trade off of capacity, weight, cost, and form factor for a product. Standardized batteries will result in products that are worse in 1 or more of those categories.
The benefit standardized batteries have over those trade offs just by increasing longevity of items and in turn reducing waste I will argue day in day out make it worth it. Those metrics are worth zip in the grand scheme of things given what we are ruining in order to achieve them. Stop breaking the world just so you can have trinkets.
Consumers prioritize capacity, weight, and cost over longevity. We are simply making the best devices we can for consumers. Phones make up a tiny percent of the waste humans produce. There are much more high impact areas that should be focused on if you want to reduce the waste output of humanity. The bias against waste of phones in due to their cost instead of the amount of waste it is.