Is there a reason why the exclude from nav attribute is hardcoded and not passed as an optional parameter?

It would appear from my limited knowledge that we could pass the attribute handle in and then allow developers the ability to filter the autonav on a number of attributes not just the exclude from nav.

It seems like in order to filter the autonav by another attribute then you currently need to create your own block or do the filtering in the view.

I'm currently looking at a 5.7build but think this is valid for 5.6 too.