I think they are terrible for the type of riding I do, except in very off-season and/or hours.

But I still encourage them as they get the sedentary folks moving at least. Anything that gets people to ride is a good thing.

There is actually a popular mup/bike path near my house, I want to try riding on it at night, when it would be deserted, but my wife forbids it as she thinks it's not safe.