The changes are being implemented under the Sporting Code Article 20.1 which states that the driver must 'drive the car alone and unaided'. As such the FIA is particularly seeking to ban information which assists the driver to tweak his driving style through particular corners or sectors, where they may be losing time to rivals.
Some are seeing this as a disadvantage for younger drivers entering the sport, although that seems something of a leap. Experienced drivers will have to learn how to race without these messages, younger drivers have nothing to un-learn, so there's likely to be little or no performance gain in either direction.
The use of pit communications to assist the driver in planning his defence or attack against another driver, to tweak his race line and touch points to gain some speed through a section would be something advantageous if it were being used by one driver only. Given that it's use is universal I can't see a solid reason for banning it.
And whilst the list of allowed and banned conversations is not exhaustive there remains the spectre of drivers receiving penalties for messages which the team believes to be allowable and the stewards deem outside of the regulations.
Rather than a useful tool we face the prospect of just seeing the radio being used for drivers complaining about each other. And that would be a shame.