I am a bit ignorant in this subect but hasnt always been the AmigaOS 3.1 the API standart?
I mean if you cleanly follow the 3.1 API, an application should be portable on all others very quickly.
Wasnt the 3.1 API the mother of all this NG descendants anyway?
Why define a standart that is already there?
If you are sticking with a 68K Amiga, there isn't much room for potential growth and 3.1 would do most people. For those who are moving forward in whatever Amigaoid OS they prefer, there needs to be new standard for the sake of the community and adding on top of that as the path forward as time marches forward.
BTW you can define any standart, but then there is the will of the programmer to follow it. Many programmers (not all) wish that their app is only available to a specific NG system so that their NG choice has leverage above others.
It's up to them if they want to participate, but if all Devs were like that, it would clearly hurt all platforms, greatly. There are not enough Devs in any one camp to push things forward and mutual help is the only way to make things better for everyone.