I'm vaguely curious why you think the age of a design has any bearing over its quality. Manufacturers don't make radical changes regularly as the bicycle frame is a conservative and simple thing (unless you're Mike Burrows or Graeme Obree).
Ribble have found a winning design with the Gran Fondo (and their winter frame, which wouldn't have looked out of place 30 years ago and certainly isn't moulded), so why hack about changing it? It's not like it's going to be ridden in the pro peloton, where chat about the latest aero improvements or whatever is largely marketing gubbins designed to flog expensive bikes to the easily impressed.