The existing trains do have a massive workload, you are not wrong there. In this country we do like to 'sweat the assets' as they say!
Even if the 175s were running just fine, the Newquay branch cancellation this morning was not a 175 related issue anyway, the 175 could have been running just fine but due to the aforementioned incident in cornwall it still would not have run.
I do think the public understand that the trains have to be in a fit state to run. Yes, people are fed up of reduced timetables and short trains, but the question really is would you rather a *pretty* reliable service with the current stock or potentially have a 175 that isnt quite ready for service sit down on a branch line and cancel the service for the whole day?