The aim and use-cases for ALSA and Jack (and desktop sound servers like PulseAudio) have always been distinct. This is my take on it:
ALSA is the low level sound driver that interfaces to the hardware. The equivalent on Windows, roughly speaking, is ASIO. ALSA does have some advanced features under the hood which extend beyond this, but its primary role is to act as the interface between the hardware and applications. Like ASIO, ALSA normally only allows a single application to access a device at a time. This means only one application at a time can play back music and record.
Jack is meant to it on top of a driver layer, like ALSA, and provide advanced features such as routing and tempo distribution. This includes the ability to easily route multiple applications to and from one ALSA device to allow simultaneous use. Jack integrates well with ALSA already and so, arguably, your request has already been met.
Jack is not good for Desktop audio. Jack is designed for an environment where the user is directly controlling and configuring the audio and MIDI routing, with fine-grained control. This is not useful for desktop audio where people expect things to “just work” without complex routing needing to be configured.
That is where sound servers like Pulseaudio come in. Pulseaudio has many features but, basically, it takes an opinionated view of audio routing and sets it up for you automatically. Note that it often gets things wrong, especially on pro-audio setups, but for the majority of users it works well. Pulseaudio is also designed to work with ALSA.
The issue comes when you want to use both pro-audio routing with Jack, and Desktop audio with Pulseaudio as the two are slightly incompatible and you can’t (or couldn’t) use them at the same time as they both want to take exclusive control of the ALSA device. There are solutions to that which work well, but often involve a bit of configuration to work.
So, if I can interpret what you probably actually want, I don’t think it’s anything to do with ALSA, per se. And I can’t see the scope of ALSA ever changing. What I think you actually want is a unified audio environment which seamlessly works as a desktop sound server which “just works”, and can be used with audio production apps in the same way as Jack does, allowing fine-grained control of complex routing.
That system is Pipewire. It, basically, aims to replace Pulseaudio and Jack with a single, integrated system for audio and MIDI (and also video). It is still, IMO, not yet fully mature, but it is getting there and, as @ccaudle points out, it’s increasingly becoming the default on many Desktop Linux distros.