Oy, don't you be trying to scupper the long-awaited improvement to Elsecar's services!
Elsecar isn't getting an extra train as such, it's just having its stop on the Sheffield-Huddersfield line reinstated a mere 14 years after it was bafflingly withdrawn, so we had the farcical situation where Sheffield-Huddersfield trains stopped at every station except Elsecar.
Elsecar and Normanton aren't really comparable anyway as, according to a work colleague who lives there, Normanton has a fast and frequent bus service to both Wakefield and Castleford, which runs every 10 minutes so and thus will connect with the train without too much of a wait. Yes, you could look at stopping some of the fast Barnsley expresses there, but once you start stopping fast trains at relatively minor stations, they cease to be express trains!
Well, of course, I would far rather Normanton was provided with a decent service than other stops suffer a setback.
That said, I can't possibly agree with your argument. Normanton does indeed have a good bus service to Wakefield and Castleford, however the main rail market is to Leeds, just as I suspect Elsecar's is to Sheffield. It cannot be logical that one of the most well patronised of the intermediate stations on the route is stuck with an hourly service when other stops with fewer passengers have half hourly.
It seems inexplicable that Barnsley is regarded as so deserving of 'express' trains that it is deemed acceptable to leave other important traffic generators with an inadequate service. The only explanation I can come up with is that SYPTE regards the Hallam line as some sort of fiefdom do the detriment of other users.