1969 saw the first man on the moon through Apollo 11. That increased fascination with rocket flight, and a model rocket industry took off. In high school in the early 1970's, I built and flew my share of model rockets. Then motors could be obtained by mail and were very reasonably priced, they were not considered hazardous materials packed several to a mailing tube.
1927, Charles Lindbergh solo flew the Ryan Spirit of Saint Louis across the Atlantic, which then was as spectacular a news as the first space flights and lunar landing. This and developments in aviation helped to kick off model airplane building and flying. This IMO helped to fuel the world's love of free flight aircraft and introduction of small ignition engines helped to further spark love of model aviation to those who could afford.
Advent of and expansion of jet commercial and military flight helped to spark a love affair with modeling jet like aircraft. Carl Goldberg's 1962 Falcon 56 trainer was a sensation as it had jet like looks and could accomodate many different engine and radio configurations. Other manufacturers used similar themes with their aircraft and offered counterparts in both shoulder wing and low wing.
Advent of the color television and affordability in the latter 1960's helped to glue many a child to TV programming. Record players gave way to the portable cassette, which became practical in the 1970's, nowing allowing kids to carry their tunes with them, along with portable transistor radios of the 1960's and on.
Today it is the Internet and portable video graphic interactive gaming through the Internet that enthralls kids.
Overall, it is the interests of people overall that have changed, and aviation modelers have become a smaller minority. Watching an airplane fly still enthralls me as it did in the early 1960's. Overall I guess it is what we grew up with that attracts us.