As I recall, the entire system is run off the 48vdc and it is regulated down to the lower voltage on each node board.. So, if you were to disconnect the 48v to the playfield, all the electronics on the playfield would be non-responsive.

Gottlieb did it with full AC disconnect to get their UL listing. At one point, Data East games (or were they Sega?) were shipped with a Fish Paper/Cardboard bezel encasing the entire cash box area so there was no access to any voltage other than what was on the coin door. I don't think you could even reach the tilt bob. Then either Williams or Sega came up with the idea of disconnecting the higher voltage secondary AC from the transformer. Which again, made sense since the transformer was located fairly close by the door hinge. Earlier Interlocks were there only for Memory Protect circuits.

If everything is now 48VDC or less, there is no requirement for the disconnect. I would question the move of the power switch being UL related. It was never an issue as long as all connections were properly covered and dead metal grounded. But moving it to the head eliminates a butt load of wire and hardware to save on cost. And regardless of your thoughts on the move, it makes total sense as an engineering design point.

Anyone know if there is a service outlet in the head now?

Every item on the Main AC input must be a UL listed component for the machine/device to get UL approval. This includes wires, fuse holders, EMI Filters, connectors, etc. Metal plates used to mount AC power devices must be grounded. All of this adds to the cost of building a game. If you can eliminate it, not only does it becomes easier to get UL approval, but you save money at the same time. So, YES, Using a UL listed power supply which encases all the Main AC and only outputs lower voltages, makes getting UL approval a lot easier. It may also help on the FCC Part 15 end since wires become antennaes and can radiate RF emissions making it harder to get it to pass for residential use.

Don't think these things happen only to save a few cents on the BOM.