The BR Manager who cut it from 5 trains to 4 admitted on more than one occasion he also lost 50% of the revenue!
The crux of the whole rural line thing is that if you have them they have to be used properly otherwise its a total drain on the taxpayer. As an occasional scenic ride its lovely but the HoW produces few real "outcomes" due to how its run. On many other rural lines the last couple of decades has seen the rise of the "city region" and commuting by rail from rural areas into provisional city centers has grown very strongly. Of course the HoW has been denied this by the truncation of the Central Wales line from Pontarddulais to Swansea Victoria. Going to Llanelli was a huge mistake (sorry Greenback), the largest town in Wales without a railway station- Gorseinion (pop c17,000) was on that stretch plus the western suburbs of Swansea, the University and ironically it terminated in where the city centre of Swansea has migrated to the SA1 redevelopment area.
It clearly cant be operated at the lowest possible cost as its part of the mainstream franchised railway over NR track. The Heart of Wales Line Forum have been campaigning for a number of years to be allowed to try and run a vertically integrated micro franchise over the line with stock stabled at Llandovery overnight producing a better timetable including commuter timed arrivals into Swansea.
The deep rural line debate will remain forever sterile unless something new like this is tried.
This may come as a shock, but I agree! Llanelli was always a 'branch' of the HoW, the original route did pass through many of the more affluent suburbs of Swansea, like Dunvant and Killay, before running along the foreshore of Swansea Bay alongside the old Mumbles Railway.
I have little doubt that there would be quite a bit of revenue from this section the line today had it survived. As you say, the old Swansea Victoria station was much closer to the modern city centre than High St station.
I will take issue with one point, though! The SA1 development is to the east of the Tawe river; Swansea Victoria is now the site of Swansea LC2 leisure centre, next to Swansea Marina on the west of the river. But that's a bit of nit picking! Sorry!