Danairboy,
Do you seriously think BA or any other airline would stop flying to a destination if it made money? Or put a smaller aircraft onto a route if it could sell the seats on a bigger one profitably?
A full aeroplane is not necessarily a profitable one, as has been discussed in many a thread on this forum.
You could argue that placing a smaller aircraft onto a route in a bid to make it viable demonstrates a commitment to flying to that place, and a determination to stay on a route.
Besides which, why does a smaller aircraft represent a downgrading of a service? If I fly out to Boston on a Virgin B747 and come back on a Virgin A340, I see no difference in the service. It is simply a question of matching aircraft and capacity to the demand for the route.
1L.