Well, I guess an opel was overdue(IMO the Zafira would have deserved the title back then), and the "Opel eye" system will be seen in many cars soon, I guess. I do agree about the "bid and heavy car" thing, but in 1970ies oil crisis, the Mercedes 450 SEL 6.9 became COTY, the probably least economical european car ever ;)
And honestly, the Fiesta is lightweight and good looking, but apart from that, not that inovative as well, as you point out. But you know, much of COTY is done by journalists driving these cars around a track, and maybe here the adaptive damping and probably teh powerful 2.8 V6 AWD made the game for the Insignia.
However, there are statistics that actually many COTY's became sales flops, ot at least, not very successful (Simca 1507, Lancia Delta, Ford Scorpio, Fiat Brava among the more prominent), or at least as title quite easily forgotten if sales were good (do we really remeber Renault Clio[twice!], Alfa 147, or Peugeot 307 being COTY?) so maybe the whole title is not worth anything Marketing wise. A nice source for debates for petrol heads like us, but that's about it.....