Why would anyone need the integration? I mean in fact: MORE integration? The systems are already integrated to the optimum degree and as a heavy user of both I find it hard to figure out what additional value further integration would bring.
The only thing that comes to my mind, but not to my "user's mind", but my "business mind", is cutting down on time and costs on development two separate apps - if the systems are integrated, I presume one app would suffice and I guess it would be cheaper and faster to develop than two separate ones.