A number of issues...
We have a road here in Eugene that was put on a "Road Diet".
2x2 (4 lane) road converted to Bike + 1 + Center + 1 + Bike.
At first I thought that it was absolutely preposterous. How could the city possibly think that a 4-lane road could be effectively replaced by a 2-lane road?
However, the reality is that people who made left turns effectively snarled traffic, so it never was truly 4 lanes of flowing traffic. There is at least 1 major shopping center interchange along that section of road which was always a mess. By reducing it to one lane of flowing traffic + a center turn lane / merge lane (merging is legal in Oregon), it may actually make it easier to get in and out of driveways, and the overall traffic flow might be better, or at least not any worse.
The other thing about that road is that there is a semi-parallel road about 2 blocks away with bike lanes, and an off-street bike path. None of the roads go straight through that section of town. But, there would be benefits of encouraging cyclists to hop off the main roads onto side roads.
As a young bike commuter, I rode on the same roads that everyone else drove on. A bit of exploring, but I had struggled with that 4 lane road above.
As an older bike commuter, I don't ride through that section of town as frequently, but I'm also learning all the bike friendly alternatives.
One thing the communities need to do is to encourage cyclists to find the more bike friendly alternative routes.
I don't see cars hopping off the main thoroughfares to go screaming along residential routes. One of the reasons is the cars inevitably get tripped up by stop signs and left turns (which in some cases may be easier for bikes).