I do think the ECML is a different case to the WCML, I agree London - Leeds and Edinburgh are the main flows, but the eastern legs, Lincoln, Hull, Teesside/Sunderland add between them roughly 18 services per day each way. Some Hull Trains services are already 10 car.
People dont like changing because they have learnt that any journey that involves a change of operator comes with a increased risk of problems magnified by the silo mentality that inhabits the current system. Other countries seem to manage connections much better than we do. To me it is one of the simple things that GBR could address quickly without spending loads of money.
However if you removed these Eastern end points and replaced it with 18 services to Edinburgh calling at the southern end at Newark (for Lincoln), Doncaster for Hull, and York for Teesside and Newcastle for Sunderland and Hartlepool (or maybe Darlington?) then normal main stops northwards you waould create other problems. Hull Doncaster services are already busy, and dont ever call at Howden or Selby (OK maybe one a day for route knowledge, not sure). York - Tesside and Sunderland, Teesside means TPE which are already overcrowded and 3 car, Sunderland and Hartlepool will mean changes at Darlington or Newcastle.
So these services are useful, and I think the places served would be worse off if they were removed. As with anything like this you will not get extra local services to compensate, and some places will lose connectivity completely.
The only question mark would be GC West Riding services, and there are alternatives, but they do provide a lower cost route for price sensitive customers in the same way that Lumo do. I do wonder why LNER continue to serve Hull when Hull trains offer a better and cheaper service most of the time, but thats one return journey every day.