Why no "Saved Scenes"or "Goup/Volume Presets"?

This seems to be a pretty simple add to the controller app. I am really questioning why this feature does not exist.

I think part of the reason is in how Sonos working, that being that each speakers stores all the data for the system. The original speaker/devices Sonos produced are still in operation and don't really have the hardware space to do much of anything new like this.

The other reason might be that it makes more sense for this type of thing to be done with 3rd party tools, so that users can combine Sonos functions with other smart home functions. IFTTT, smartthings, yonomi, lutron are examples of smart home apps/products that can meet the needs here. I personally like lutron as it fully controls all my lights and speakers and is easy to use. I don't mess with it very much, but I have a schedule to wake me up every more with a few lights turned on and a music station playing in a couple rooms at set volumes. You can also set routines that are activated by voice command or the press of a button in the lutron app.

Not to argue the technical merits of your reply but if we can manually group and adjust volume from the Sonos App Controller there is no reason it could also not store a preset's configuration and issue the command needed.

I don't think I said this clearly enough before. All data is stored on the Sonos speakers themselves, nothing on the controller. This was done intentionally so that any controller can be used. if you start storing preset configurations or any other data on a controller, then the preset would only be valid with that controller, or you'd have to come up with some sort of syncing process. It really just adds a lot of complexity to the system and can lead to a lot of limitations and issues as you further develop the system.

The 3rd party systems I mentioned earlier all have a central device that stores the info (smartthings, lutron), cloud based storage (IFTTTT), except Yonomi which basically uses your phone as server (I think). It's limited in that regard. I could see Sonos starting to store some data in the cloud, but that also comes with drawbacks. It's maintenance for Sonos isn't great, and it requires a user's system to be connected to be used, which a lot of users don't like.

Maybe they find room on the devices, maybe cloud, I don't know. I was answering your question of reasons why it doesn't exist currently.

As far as 3rd party apps - most are pretty limited in functionality and (I assume) are using API's made available from Sonos.

Yes, APIs are used. The limits in functionality depend on the 3rd party tool used. I'm currently using lutron to do all the functions that you listed in your requirements. Set group, volume in each zone, and station/playlist collected. Well, and scheduled, which you didn't mention.

This feature really is needed and would also enhance the Sonos differentiation in a crowded marketplace. Frankly, new features like this that differentiate from competitors offerings and set the bar higher are what prevents Sonos and their solution from being looked at as another smart speaker commodity.

I've seen such statements made about missing features many times. Headphones, portability, DTS and Atmos, etc. Some claim that Sonos isn't implementing new features fast enough, while others claim they are moving too fast. Who knows.