Klein had aluminum bikes out for a long time with smaller builders like Charlie Cunningham making custom aluminum bikes before Cannondale.
It was true for the short/steep angled road bikes but in the long wheelbased touring Cannondale it was a fantastic improvement with the only competing alternative big steel tubing mtn bikes. I remember meeting the guy who made/owns Bullseye hubs and he had a super long wheelbased custom aluminum bike. Anyway taking that first Cannondale touring bike out on trails with 35mm tires, solid as anything but a lot lighter and the ride wasn't harsh. It was harsh if you have 16" chainstays and 22mm tires pumped up the 120psi. And you're right the designs have gotten much better especially with the carbon forks.