Often, if older standards become obsolete, it's because they are superseded by newer technologies. In the past networking was done using coax, instead of the twisted pair used today. Why did they use the more expensive coax? It doesn't look like the twisted pair technology didn't exist back then, so technological advances don't seem to be the reason.
Electronic – Why were coax cables used for networking
Coax was used for its controlled impedance, its bandwidth and its self-shielding properties.
Sure, twisted-pair wiring has existed for a very long time, mostly used to carry audio frequencies in telephone wiring. That isn't where the technical advancement was required. In order to compensate for twisted-pair's lossiness and impedance issues, major technological improvements in the electronics used to interface to it (such as high-speed adaptive equalizers) were required in order to make it more cost-effective than coax.