It’s hard to over-estimate the power of the relentless onslaught that Shimano unleashed on the bicycle component market in the mid 1980s. It was a two pronged attack. On the one hand there was the widely recognised and appreciated, peerless, technical performance that came from Shimano’s ruthless control of every element of the drive chain. On the other hand there was the equally important (but rarely recognised) aesthetic design and styling of the components. It was a killer combination - and was very unexpected - up until this time aesthetics had been treated with a certain amount of scepticism.
The Ultegra 6400 series was, in many ways, the high point of this attack. It was, of course, totally technically competent and a good step ahead of anything SunTour or Campagnolo had to offer at the time. But it was also extremely beautiful, beautifully finished, beautifully coloured, combining classic detailing (like the bands in the centres of the hubs) with ruthlessly modern forms (see the rear derailleur pulley cage plates) in a seamless whole.
Even today it looks good enough to eat.