You are looking at the situation from the wrong angle. What electrification has done is provide infrastructure that (almost everywhere else) increased patronage. Without the 319s or something like them being available, the electrification would not have been done yet.
At the moment, there are limited services and the timetable has not been fully 'electrified'. When the TPE route and MVC-PRE-BPN are completed all the north-western and many of the trans-pennine local and regional services will be transformed. That will be the time to judge whether things have improve.
Normally electrification has been done on lines with potential for significant growth. North West electrification and TransPennine electrification is in areas which have seen exponential growth without electrification over the last 10 years. So it's not possible to compare it with previous schemes, these are likely to expose the 'electrification sparks growth' as an old wives tale.
Yes without the 319s electrification wouldn't be done. Electrification was an alternative to an order of brand new DMUs when DfT realised they would be spare EMUs as a result of Thameslink and they were proposing ordering new DMUs for Northern, TPE and FGW.
The December 17 timetable for Chat Moss is set to be:
* 3tph Liverpool to Wigan - 1tph continuing to Preston/Blackpool
* 2tph Liverpool to Yorkshire/North East service via Victoria - alternate services running non-stop between Lime St and Victoria
* 1tph Liverpool to Manchester Airport stopping service.
I think transformation of services will happen as a result of the Ordsall Chord opposed to electrification, that is the one thing which will allow a complete recast for the Manchester area with more services. Indeed most of the TPE improvements are set to occur at least 3 years before Manchester-York electrification.
Of course, not all lines can justifiy electrification or even new trains so it's inevitable that they will get 'previously cherished' rolling stock until that is life expired. It's sustained high levels of patronage to prompt DfT to commit large capital sums for investment.
I think you're wrong in the case of Chat Moss. DfT thought Chat Moss should be electrified over the CLC for 2 reasons:
1. Chat Moss could be used as a diversionary route for WCML services to reach Manchester and Liverpool if it was electrified.
2. They thought it would help with overcrowding on the CLC line as there would be more Manchester-Liverpool services. However, so far this hasn't proved to be the case despite the CLC line now having as many services as it will have in December 2017.
It's a bit like the line through Stone being electrified. It's wasn't primarily because of loadings on local services, it's primarily to allow an improved Intercity services on the WCML.