UX is usually worse for non-customers because the main product offering of many online services simply cannot exist without strong relationship with customer (probably Quora is not the case). Because of that, experience of registered users receives much more attention. Most of the world is happy with it and is not going to deprive themselves from cool stuff on privacy grounds. I'd say it's counterproductive to fight against collecting personal data by corporations, because corps do need it to make service better. Instead, it should be better regulated, possibly, similarly to financial organizations by requiring independent privacy audit etc.