Not quite sure what point(s) you are making?
Transmission of QNH by voice is no more primitive than transmission of cleared altitude or heading or speed by voice.
Yes, in theory it could all be done by digital data transmissions, where the cockpit QNH setting simply updates in real time. (Ditto cleared levels, headings and speeds). But we all know that such a system would not be infallible either, and even more cross-checking would be required.
Altitude could be defined by GPS instead of barometric pressure, but like-wise, that would bring other potential problems and traps.
The thing is, we already have a pretty good system for air traffic control and altitude definition. Not infallible either, but very well tested and practised - we all know what to do and how to do it. PM listens to the latest meteorological report and writes it down, including the QNH. When ATC clears the aircraft to an altitude, the QNH is cross-checked with that independently achieved information.
What is starting to happen, I think, is that training is being slimmed down and skies are getting busier, duties are getting longer, and human performance and CRM is suffering, (and not just pilots). The PM in this incident does appear to hesitate on his read-back at one point, so I think he must have suspected that there was a mistake somewhere. But for whatever reason, it was not queried or followed up.
Having instructions transmitted in two languages instead of one, (at a very complicated and busy international airport, no less), prevented all pilots from hearing the QNH given repeatedly to other aircraft, which would have flagged up the error.