TPE used to run later trains from Newcastle, there used to be a 0215 from Newcastle to Manchester Airport. It did have a tendency to be a bit colourful until Darlington, but that isn't why it got binned: it got binned because Network Rail wanted to do engineering works. The 2200 Kings Cross-Newcastle was almost binned north of York for the same reason (and for a while was split at York into a separate service at 0055, frequently bustituted).
The big issue I've found is that the 2220 Northern service now terminates at Darlington, just in time to watch the last Middlesbrough train leave the station, whereas it used to go through to Teesside (I definitely remember it going through to Redcar when I first moved to the north east).
Beyond that, a big issue is geography. Durham and Darlington only really see long-distance trains these days, meaning the last train is when the last long-distance train is; 2250 isn't so bad in that context. As for the Tyne Valley and the Durham Coast, the simple fact of the matter is that later trains will mostly be carting fresh air around.