Just how to preserve this unnatural state of affairs is what is being debated. If we don't understand this fact -- if we create laws or technical standards that favor one type of packet over another -- we risk foreclosing all sorts of interesting and valuable applications in the future that no one has even imagined yet.
So no, I don't think it's a good idea to promulgate standards that work well with transient messages and datagrams but not streams. If that's true of LTE Direct (and I'm not familiar with the spec, so I don't know if it is), then that's a problem. We've already baked that behavior into the architecture of the Internet itself, and it's only going to become a bigger issue as time goes on.
I have absolutely no faith that the government is capable of responsibly managing this ecosystem.
Let the nerds work. Do not bring regulators in whenever architectural decisions need to be made.
You wouldn't want to do this for streaming traffic, as it could negatively impact the experience of the device with the strongest coverage. But you could do this for traffic that has lower performance requirements.
Paid prioritization has existed over the course of the entire Internet. I happens every day- and it is known as peering agreements. Would you characterize the history of the Internet so far as "stifled growth"?