In the A320 the display of ILS GS and LOC symbology on the PFD is incompatible with using the autoflight system to fly a non-precison approach. The ILS may be hard-tuned but the crew will not see the data unless they select the LS pushbutton or switch the Nav Display over to ROSE LS mode. If they do press the LS pushbutton after loading an approach with vertical guidance, they will get a flashing amber V/DEV message on the PFD to highlight the incompatible selection. I do not have experience of any 'FMS coded' visual approaches (RNAV visuals in other parlance?) but I expect that the FMGS behaviour is the same.
In the case of a classic visual approach, with just the runway selected in the FMGS, the ILS will have auto-tuned (the FMGS will know that it is an ILS runway) and the data can be displayed on the PFD without any advisory messages; the selections are compatible. However, by coding the visual approach trajectory into the FMGS it has effectively been transformed into a non-precison approach, and the selection of supporting ILS information is not as straightforward.
Bearing in mind the above information, just try writing a procedure to turn what may sometimes be a valid technique into a SOP. You would have to decide at what point it would be safe for the crew to start making fundamental changes to their EFIS set-up in order to discard the FMGS guidance and switch to ILS data. You would also need to consider if your procedure is robust enough to cope with the different cases of a non-ILS runway, ILS not available and a full-up ILS.
I also think it is worth pointing-out that hard-tuning the ILS requires manual entry of data from a different approach and introduces the chance of incorrect data entry. What if the FMS Quiet Bridge approach to 28R had been selected, but going to a different plate to obtain the ILS ident resulted in the tuning of the ILS for 28L? The technique is valid, but it is not a completely threat/error free.
Perhaps this particular occurence has found the flaw in FMS coded visual approaches? Rather than just censure the crew, the industry needs to look at what lessons we can all learn from this. Would the inclusion of runway lighting configuration on the ATIS at airports with close parallel runways be worthwhile?