I would suspect that, given most GA products are consumed in the US of A, the fear of "Product Liability" suits has hampered the development of anything new from the Piper/Cessna, Lycoming/Continental camps. I.E. why change something proven for something new, when you can spend time concentrating on making it for less money instead?? Sad, but probably true.
The dominance of the PFA/LSA class by eastern european 2 seaters with rotax's up front promises to change the bottom end of the market quite dramatically; Maybe Cirrus and Diamond will do the same for the middle market.
On the subject of "the computer says no" I seem to remember Ian Seager of Flyer writing eloquently about a trip across the southern North Sea in a glass cockpit cirrus, only to have a minor lightning strike stun the avionics, leaving only a compass, AI and an altimeter to work from. Perhaps things have moved on...
However, even if I had the £250,000 necessary to buy an new 'plastic fantastic', I'd probably still go with an older airframe from one of the usual suspects (piper/socata/cessna) instead and spend some cash on bringing it up to 'as new' condition. I take onboard the comments about having to spend the difference on airframe bits but, against the depreciation cost of ownership from new or nearly new, this seems to be a price worth paying.
Just my opinion based on my limited experience of ownership.
