I actually like the idea of a floating title. Yes, it logistically makes things very difficult as far as having wrestlers work on different brands.
But I think the upside is that you can always keep things fresh by simply jumping from brand to brand. For womans and tag divisions you generally have the same 3-4 people or teams wrestling over and over and over again. No matter how good it is, eventually it does become stale (ie New Day and the Usos). But if you have the ability to float over to Smackdown for a month to feud with the Iconics, then even to NXT to feud with Io and Sane, then you can really keep things fresh.
Its more work but I think its worth it if they can pull it off. I'd frankly consider doing that with the womans single title too. But if they can't pull it off then yeah... probably easier to just have the tags all on one brand