For the WooCommerce Stripe Payment Gateway extension, there is a checkbox on the checkout page, underneath the credit card form, which gives the option to "Save to account".
I propose that this checkbox be configurable via the WooCommerce payment settings, allowing the admin to set it to checked or unchecked by default.
In my case, I do not allow guest purchases, so every customer must create an account in order to purchase something from my membership store. Especially since most of my products are recurring subscription products, I would much rather have their card info saved to their account by default than to rely on the customer to tick that box during checkout.
With a simple setting in the WooCommerce Payment Gateway settings, this checkbox could be either checked or unchecked by default, eliminating user error.