IMHO raw data practice is required as long as raw data flying might be required in an emergency situation.
On most aircraft I have flown so far the flight directors are gone in a battery-power-only situation, so it seems prudent to mee to practice flying without them.
In an ideal world this practice would be done in a simulator, but as many companies won't schedule more sim time than the regulations require, and that time is completely filled with other "required training", this probably won't happen.
I don't think raw data flying compromises safety when limited to VMC and "other than high density" traffic situations.
I wouldn't practice it at LHR or FRA.
I am not a grizzled veteran (flying the line for 15 years) and rather feel that copilots should switch off FDs (even APs/ATS) more often. I very often see FOs switching the AP off at 700 AGL. I probably couldn't hand-fly any ILS if I always let the AP do it's job....)
I also agree that "real" raw data is hard to train, as most glass cockpits offer a lot of helpful stuff even when the FD is off. (speed trend, flight path vector, etc.)