I think it's cause some companies started becoming obsessed with simplicity and making things way too straight forward imo, and the idea of what the future looked like started to change drastically as tech improved thus changing trendy design aesthetics and stuff. If i'm being real tho, I haven't looked into the history of frutiger aero too much so I wouldn't be suprised if i'm wrong about a lot of it.
Well, maybe the companies and people want things to be more practical and sleek, so they really deyasstified products over time, they take away the freshness, the futuristic from everything, I guess?