This is not the first time this has happened. Around 1970 or 1971, the networks began cancelling rural-based comedies (such as Green Acres, Mayberry RFD, etc...), and other such wholesome fare, to replace them with more “edgy” shows that would appeal to younger, hipper, urban-types - shows like “All In The Family”. It is known as the “Rural Purge”. In the space of a few years, the entire face of Network TV was radically altered by New York-based Network Execs who did not like what they saw. Many of the shows cancelled were still highly rated, but they were cancelled anyway. Yet another “fruit” of the 1960’s liberalism that was gaining ascendancy in our culture. This Wikipedia article is actually a good summary (surprise of surprises!!), and makes for interesting (and relevant) reading:
http://en.wikipedia.org/wiki/Rural_purge
Cheers!
"Westerns had already been targeted for cancellation after concerns of violence led to pressure from parents' groups to tone down violence in television, and by 1969, no new Westerns were debuting."
Yep! "The Virginian" was just too violent...