Would that depend upon the manufacturer involved, all they all cannot be producers of poor quality rail traction.
Yes and no. Looking at brand new trains, what has built for the UK in the last 10 years? I'm sure there are some decent products there, as far as the train itself is concerned, but the interior fit out is universally bad, regardless of which manuacturer built the train. This is largely due to the seats, there hasn't been a single design of new passenger seats that I would consider to be an improvement (for long-distance travel). This applies to refurbishments as well as new stock; every time I see an announcement that a BR-era fleet (or even early 2000s) is to be refurbished with 'new seats' I cross another route off my list of comfortable journeys. The Pendolinos were already on my 'avoid if possible' list due to the tiny windows (I like to watch the view as I travel) but Avanti's refurbishment made them even worse by fitting modern seats and are now on my 'avoid for anything longer than 60-90mins' list. TPE's CAF class 397s give much better window views than the Pendolinos, but the seats are in the same 'limit journeys to 90 minutes' box and for a number of years now my preferance for WCML journeys has actually been Virgin/Avanti Voyagers (the coach next to first class, which doesn't share the window alignment failures of the rest of the Voyager fleet).
The above is all related to standard class; I hardly every travel in 1st.
Against that background it remains difficult to justify investment in new trains when there are (arguably) perfectly good mid-life trains going spare.
The industry hasn’t exactly demonstrated prudence with the way a number of perfectly decent fleets have been tossed aside (350/2, 365, 379 to name the obvious ones).
The common theme there is that those three fleets are EMUs (and possibly the rather flawed 'quality score' system in franchise bid evaluations, although I'm not sure if that was actually relevant in the case of the 350 and 365s). What we really need is an electrification programme.
Out of curiosity, can you name one or more occasions a ToC has introduced new rolling stock without an announcement?
Not brand new stock, but I cannot remember whether or not Arriva Trains Wales ever announced either of their introductions of cascaded mark 3b vehicles (first was TSOs and DVTs, replacing mark 2s on 'Y Gerallt Gymro', and second was an additional set of TSOs used on the Manchester - North Wales route).
If the Class 175 are as good as they are claimed to be, why are they wanted to be moved to a different operator, noting the fact that has been pointed on this thread that the Class 175 are still in their mid-age?
TFW needed more units which has SDO for use on the Marches and North Wales Coast line to increase capacity due to overcrowding, this came in the form of class 197's. TFW also are taking the opportunity to 'opportunity' to streamline its mainline fleet from mk4, 175,170,150, 153 and 158 to mk4, 197 and 153.
Yes, additional capacity was needed but this is a good example of the problem of incompatible coupling systems. TfW could have simply ordered 30 new trains to supplement, rather than replace, the class 158s and 175s but each type would have been unable to rescue the others - we really need standardised couplers (as the Rail Delivery Groups' best practice document for train design tries to do, but is frequently ignored). Also, this is possibly another case of franchise bid evaluation erronously assuming that 'newer' means 'better quality'.
Also, the plan at pre-COVID TfW was for even greater standardisation - essentially only 197s and 170s (the latter being instead of 153s, and being restricted to Heart Of Wales and S.W. Wales services) with just three mark 4 sets on Holyhead-Cardiff to break the blanket application of class 197s almost everywhere else outside the 'Metros'.