I think the points about prioritization are very fair. As far as I understand, what your suggestion ultimately comes down to is this:
We need new client teams that are dedicated to build stateless clients since we should not expect current client teams to do this.
I’m very skeptical about this. The idea of statelessness should be that ultimately, most people don’t need to keep the state. That’s how we could potentially increase the gas limit (because DOS attacks due to state growth cease to be a problem and Eth2 validators will not have to follow all blocks, reducing their bandwidth) and allow several execution shards on Eth2 (because validators don’t have to follow all execution shards, which would be the case if they’re stateful).
So unless the clients reduce their target customers and only want to be useful to state serving/block proposing, they will have to provide a stateless mode.