The thing is, you can't just 'escape XSS'. You need to know exactly where the data is going to be used, and you can't know that when you store it (in fact, you could use the same data in many different places). There are infinite ways of doing XSS, so if you don't escape properly, you are still vulnerable. The view layer should escape everything by default. Then if you need a different filter, or disable escaping (for wysiwyg for instance), do it manually.