AAD currently requires a strict directory scoping. We can investigate options if this is a popular request.Brian Lacy commented
This is very important to me as well; it's very frustrating that I can't manage all my subscriptions in one place on the new portal!
We have made some great progress on this idea and most of our services today do support move resources across groups.
We are still working towards 100% support and while we do that it would be great if you can help us prioritize the missing services.
Please file individual asks on each service category present in uservoice and vote for it.
Azure Portal Team