It’s a natural progression of Radio. Consider it evolution of RF rather than change. Way back in the day, AM was the defacto modulation type. AM was noisy, but it got the job done. In 1933 the FM modulation type was invented and introduced into Radio. FM solved the noisy issues that was prominent in AM. For decades FM ruled the radio world and still does in many cases, but digital is here to overtake the modulation throne. Since digital is basically a transmission of data rather than raw voice, it can transmit more in a payload when a radio PTT is pressed. Things like user Identifiers, GPS positions, Short Messages, and TDMA are just some of the benefits.