Or finally digitize the whole ATC system and remove radios altogether which may be the way forward for conventional aircraft anyway but I expect will meet heavy resistance.
To the OP regarding terminology - Getting picky now, but by 'radio' we are talking about 'two-way voice comms on the relevant control frequencies transmitted via the flying machine by radio', because text or data will also travel by radio. You cannot get away from radio in this context. The only thing that changes is the format of the communication ie voice or data.
As for an all-data ATC environment? No one has time to read lines of text from all the participants. Much more situational awareness (SA) is gained through voice than just from the words - tone, pitch, emphasis, sarcasm, panic, etc.
As has been said in previous posts, if it ain't broke, don't fix it. Put a radio on the UAS that relays the calls made by the pilot/operator and the controller. That way, everyone else operating in the space knows what is going on, which goes a long way to improving the SA of pilots of manned flying machines and their confidence in the behaviour of UASs.