The 319s are rubbish, but they're less rubbish than 142s and 150s. They're more suited to this work than the 156s, too; getting off a peak-time 156, with the tiny single-leaf door, is not an entertaining way to spend a morning.
It seems that some here want train travel to be a an efficient way to get from A to B. The fact that these trains will be full of other like-minded passengers means that the train must be designed for maximum bodies and minimum entrance and exit times.
A few others speak as though having a deep comfortable seat (in 2x2 configuration of course) with armrests, tables, seats that line up with windows, power points, et al. is all that matters. They don't seem to care how long it takes the train to cover the route, (slow diesel-powered, long dwells, far too many standees for the available space etc.). I imagine that they get their seats in the morning and the train fills up later in the journey.
The 319s are undoubtedly more efficient people-carriers than what has been in use until now. I believe that the majority of users will see them as a great improvement and the moaners will just - well, carry on moaning. The 319s aren't the oldest stock in the North-west, they are younger than 142s, 150s, 156s, 508s, etc.. They will probably carry on until the late '20s unless there is a major reliability issue. Their shells are MKIII, which have been described as the best coach shell design on UK railways so they have crash resistance that is acceptable 30 years after built. Commuter trains are workhorses, not gin-palaces with flanges wheels, misguided Thameslink regulars will realise this in three years.
With the later electrification schemes completed, there will be quite a population of 319s in the NW giving the TOC benefits only achievable with scale. Firstly, they will be less likely to be sent elsewhere, and secondly, when they are replaced, the numbers involved will justify a complete update programme, probably new build, (or maybe all the 365/465s which will be ready for replacement in the South-east

just joking).