i can understand point of view of ng users as yours, to urge to concentrate on development of either aros, mos or os4, but still i cant see a practical possiblity to convince the widest user base to any of those solutions exclusively.
This has always been the problem, I think.
Even back in 1992 Commodore will have found it hard to make people use the new OS 3.0 API - but of course now we take it for granted. Developing for OS 2.04 or even OS 1.3 is unheard of.
There comes a point when the people still using the obsolete APIs like OS 3.x have to move on to stay current - it's always been that way, and always will be. Of course the problem now is what do they move on
to. To some it's OS 4, to others it's MorphOS, to others it's AROS.... but only ever supporting an ancient platform like OS 3 - even though it's the lowest common denominator, is
such a low power platform that catering to that as a primary platform will hold back all the newer platforms.
We need to push forward, otherwise we'll be forever stuck with apps that are made to run on a processor from nearly 25 years ago, and that's no way to stay current.
It's a very difficult one to call, though, and I completely empathise with what you're saying - the "Classic" is the common factor with all of us - and it shouldn't be ignored... but I think it should be treated more as a legacy platform rather than the current target platform. If something runs well on low-spec hardware, make it for OS 3 - but don't hold back progress on our multi-GHz NG machines for the sake of a 20 year-old machine.
There's no simple solution (as usual for the Amiga world....)