The bussing arrangements for domestic arrivals at LGW go back at least as far as early 2015. I thought the new Pier 1 at LGW was going to include direct access to domestic baggage reclaim, but obviously it hasn't happened.
The regulars (I did domestic arrivals for every week for nearly a year) work out how to increase their chances of being first off the buses (in order to get the lift) when they get to the terminal. Being one of the last off the plane can be an advantage especially as it minimises the time stand on the bus. The staircase at the terminal end is only 2 floors and it's no worse than getting off the air-bridge at one of the Pier 2 gates and then finding the escalator is out of service, a frequent occurrence.
I'm now doing international arrivals every week at the South terminal and, on balance, I think I prefer the domestic arrivals experience.