Now that we look at the designs from 20-30 years ago, they stand out simply because they're outdated. In another 20-30 years, someone will write an article about the beauty of "glass slab" phones of the 2020s.
We also tend to cherry-pick outliers. You can find some beautiful designs in every decade, but they're not necessarily representative of everyday life. There's a modern-day company making portable cassette players that look like this:
https://cdn.mos.cms.futurecdn.net/MfFjHvcZjFzZLRPa4p7QZm-970...
Striking and prize-worthy, but not how we roll.