Think you've just hit the nail on the head there as to the unpopularity of the Hitachi SET (Not nessesearally the IEP, but the train that will result from it.)
I'm Glad i'm not the only one to notice and say that then. They just don't impress me at all, the ride still isn't that perfect - especially in the tunnels, the interior feels cheap with the steel effect plastic panels - ones covering the PA screens are the worst for vibration, and rather the lighting seems rather dingy and shadowy in tunnels. Certainly not as good as the quality from Siemens, Alstom and to an extent dare i even say Bombardier.
If... if i was to suggest one thing to Hitachi, that is to do a similar idea that Siemens took on board when producing the Desiros. Take a Mk3 back top your factory, see what makes the Mk3 sooo good, and try to build on top of that. Not, praise the Mk3 for 5 seconds, and then say how good the japanese technology is, because at the end of the day, this isn't japan.
And if your wondering what the Siemens connection is, back when Siemens were awarded the contract to build the SWT Desiros, Siemens took a reliable every day old 4 VEP from Wimbledon - took it to it's Wildenrath test centre for assessment, fitted calibration equipment to it to see essentially what and how it was so reliable. Took the data resulting from those tests, learned and built upon this with the Desiros. Hence another part of the VEPs test life was to calibrate the 750V DC equipment installed by Siemens to test it out for the Desiros. Now that is clever forward thinking, and the result is a reliable quality product!