FP, glad to see we share some frustration!
Don't get me started about the FMS!
As I have tried to show in the posts, the different flight management systems, use data differently. This hasnt helped in moving this forward, as everyone wants their system to be the standard.
Being involved in standardization myself, I know what you are talking about. It's a dreadful slow process to get things aligned, especially when the FMS is involved.
All of the capabilities you are talking about, are already there, trust me.
I know! But because everyone is doing it their own way there is no interoperability. Not between different aircraft and not even between different systems onboard an aircraft. You want to design a new application that needs access to (not changing, just looking at) the current FMS flight plan? Can't be done. You want to extract a published route from the database? Can't be done either.
If we want to make progress in air traffic control with respect to flight path optimization, the FMS needs to be interoperable with the outside world. Otherwise we will be stuck to static routes forever, meaning that CDA's / OPD's can not take into account the traffic picture. That means either no optimized descent, or a lower throughput on the airport. Or a CDA until 3000ft and then some 30 odd miles vectoring at low altitude and low speed (preferably so slow that at least some flaps have to be selected) while pouring the fuel overboard just to re-achieve a nice approach spacing that was screwed up because the unpredictability of the speeds during the CDA.
I would love to see the ability to code an approach path with some waypoints that can be placed freely (within a constrained area) by the FMS in order both optimize the descent profile and meet time constraints (e.g. spacing from another aircraft) at the same time by stretching or shortening the route. And when the systems is redesigned for that anyway, please make planned final approach speed, current wind speed / heading and minimum clean speed or any inside data for that matter available to an external interface as well.