I was suprised they didn't rebuild City of Glasgow, but I guess it's up to the TOC. On the plus side of that, if it was rebuilt we might not have the rather smart looking Pretendalino!)
At first I was going to say 'TOCs weren't around when City of Glasgow (46242) crashed at Harrow & Wealdstone, but then I realised you were on about 390033 at Grayrigg! (Remember there was also an 87 named City of Glasgow (006) and also a 90 (004))
Anyway, regarding the rogue Pendolino. I believe as a result of the forces that the train experienced on impact, the frame on at least one vehicle (which correct me if I'm wrong, but believe it was the leading vehicle) became distorted. As a result of this, the vehicle was a write off. As the Pendolino production line had closed, it was deemed uneconomical to build a one off driving car. I suppose it highlights the lack of flexibility/ contingency a train company has if it's relying on fixed formation units, without any substantial spare parts.
Also, while the point has been mentioned of 'modern structural standards'. People seem to think that the railways of 20 years ago were hopelessly dangerous and that all trains were built like tin cans. It's not really true. OK, Clapham was an example that mk1 vehicles had major flaws, but really anything mk2 and above have proved themselves to be very safe in collisions. On those grounds, I don't think we can comment on an 66 being any 'safer' than any of BR locos.
At the end of the day, we should be happy that incidents like this are very few and far between in this country, and most importantly, the crew in this particular incident are unscathed.