Back in the 60's when I grew up in the Inland Empire we had KMEN and KFXM, we also got XERB and KHJ. Other stations heard in the daytime included KRLA, KCBQ, and KEZY before they cut their power at sunset. We were lucky to have KMEN and KFXM, and even over 50 years ago their library of golds was larger than your typical Classic Hits format today such as KRTH has. KMEN had their Rebound Weekends, and KFXM had Flashback Weekends to match KHJ's Million Dollar Weekends. They alternated currents with gold starting on Friday afternoons instead of playing three currents to one gold like the rest of the week.
I don't believe there are only a couple hundred songs from the past worth hearing and even if I did I would include many other songs than the ones Classic Hits stations are now playing which would include tunes from the 60's and even 50's. When I do listen to oldies at home I stream Pop Gold Radio, Rewound Radio, Deep Oldies, WLNG, WSWO, and other stations that have a huge playlist going way back. Until recently I listened to KFXM online until it ended.
The first seven words of your post, rparky..."Back in the 60s when I grew up..."
Commercial radio survives on commercial sales.
Ad agencies want 25-49 year old adults.
Today's 40-year-old was born in 1983. So, high school class of 2001, college grad 2005.
What you and I grew up with in Southern California in the 60s (and I listened to every one of those stations, too) is irrelevant to what KRTH (and any radio station relying on ad agency sales for survival) needs to be doing now.