You call it laughable having to change at York onto an overcrowded LNER service. Well surely the XC stuff now from Leeds is pretty overcrowded, so frankly changing at the lovely York station onto a 9 car LNER service or even changing at Leeds onto a TPE service if travelling as far as Newcastle really is no great hardship. And if that leads to people not needing to stand from Birmingham to Plymouth ,or Birmingham to Reading due to the released 4 voyager units, then it is money well spent. There is a real over provision of services in my view around Yorkshire heading for Scotland. People like to have a train carriage where no one is sat within about 20 seats of them, but in reality, how sustainable is this? It's hardly being selfish arguing Leeds could lose direct trains to Edinburgh. Unlike people in Yorkshire, people in the south don't really have a viable alternative to XC, it isn't being selfish in arguing that Yorkshire has an over provision of trains northbound compared with the Midlands southbound.
There are 3tph from York to Scotland only 1 of which serves the major regional centres of Sheffield and Leeds. All three services are very busy all day. This is hardly over provision, it is demand driven.
What you suggest is shoehorning 4,5,8 or 9 coaches of people into the remaining busy 18 coaches at York station which is not as lovely as you seem to suggest. It’s windy and crowded with some pretty narrow cluttered platforms although I agree it has a lovely roof (take this from someone who commutes into York).
Most people who board at Leeds have already changed from another service so making them change twice in a short space of time from one overcrowded service to another is going to suppress demand and push it onto the roads (maybe that is your intention).
Cutting a well used direct service from West Yorkshire (a big difference from your politician style description of provision of services from ‘Yorkshire’) to let everybody in the south west have 20 seats to themselves (what you say everyone wants and something we certainly don’t get up here) is not the way forward.
If, as you yourself say, 4 extra voyagers will stop people having to stand from the locations you mentioned then happy days, XC are gaining 12. No need to make more people stand than they do already from York to Edinburgh.
As an end note I live and work in the Yorkshire region, always have done and I travel by train for commuting and occasional leisure travel. I see what the railways of our region need and am lucky enough to also work in railway planning for the north and know what is and isn't possible. Now, I wouldn’t dream of telling people of other regions that we want their trains to improve ours to reduce our overcrowding and reduce their connectivity and direct long distance services to suppress their demand. Why do others think it’s ok to do that to Yorkshire when it comes to XC?