Not sure how permanent it is but the leaflet I was given last time at Lgw from the airport says
"From Tuesday 29th January 2013, we're making your journey through Gatwick even easier" .. " This means that you'll no longer need to wait at the facial capture point before collecting your baggage"
Like you I wondered if we would end up with at an hour long queue to get through the cheerful souls at the UK border every time although from what you say there is little or no delay. Certainly the implication from Gatwick is that there is to be less delay than that taken to have ones picture taken.