As far as I can tell, the current limit of 15 characters for website members is not configurable. Modern password management tools allow you to generate very long passwords. If Wix creates a fixed-length hash there is no reason to limit it to 15 anyway. I would like the ability to restrict passwords to be between a configurable lower limit (eg., default 6, must be greater than or equal to 6) and a configurable upper limit (eg., default 15, must be less than or equal to 40). 40 seems like a reasonable upper limit.
Being able to configure password strength too, such as requiring at least one number, one upper case and one special character, would also be helpful but less critical for me.