Yes, I get that the cameras have utility as engineering diagnostics when things go very bad. The Shuttle and even the Saturn V had dozens of cameras at nearly every possible angle, and as the cameras got smaller there were even more that were stuffed onto the various devices... including the SRBs and even the external tank.
As an engineer, you can pull out a whole lot of information about what is happening at each stage, especially if it is a high speed camera watching stuff that happens at launch... as that is when a lot of stuff can go bad. These other cameras are definitely useful to see if something goes wrong and try to get more information visually apart from some other electronic telemetry that sometimes doesn't tell the whole picture.
I don't know where this particular camera is located at on the 1st stage though, but it is very possible to be located just above the grid fins to watch their performance as that was something which wasn't working properly on the last launch.
The PR value is definitely there too though, and you can't deny that having pretty pictures to share with the public can be useful. I have no doubt that if things go smoothly (with likely a couple second delay preview before going to the public video feed) this landing will be seen during the launch too.