It seems the forum is ignoring the extra demand that will come from Warrington West which under construction complete with a large car park that is more convenient than Warrington Central for those west of the A49. The area around the station is in the Travel to Work Area (according to ONS) for Manchester not Liverpool and the station is intended to serve the are at Omega Business Park which will be pretty huge. The idea of turn-back at Central for the Manchester services and ignoring Warrington in favour of Liverpool-Manchester direct is not realistic.
A major disadvantage of the current set-up of fast trains over Chat Moss is the need to use Lea Green and Newton-le-Willows as railheads for intermediate demand. Any new line which doesn't go through Warrington would be a waste. Same with HS2 services to Liverpool - it should serve Warrington on the way with full length trains at least twice hourly