Possibly because the train could have been so much better, but DfT became obsessed with provision for carrying crush-loads through the core. They're a step backwards in terms of passenger comfort and ambiance from the Electrostar - no carpets, no armrests, no seat cushions, no room for feet, no tables, no power points, no style.
I was prepared to be won-over, but given the door niggles, apparent inability of the driver to handle the train properly and the sheer lack of fit & finish inside the unit, the whole experience was disappointing. Exposed screw heads, boxes stuck to the walls & floors. STI clinic flooring and bare magnolia walls. Despite the lack of carriage ends, passengers resolutely refused to move far from the door areas. The driver passcom was loud, but the attention chime was ridiculously loud. Unfortunately the driver clearly had received no training on how to use the device.
I'm looking at the train from the point of view of someone who will be consigned to suffer these ghastly abominations from now until I retire. I'm not reviewing it from a railway enthusiast standpoint.