https://en.wikipedia.org/wiki/Idaho_stop
It's safer[1], and other places (California[2], Denver[3] from a quick Google search) have looked to implement similar laws.
You probably only notice when the cyclists don't take "due care" before they proceed into an intersection. Of course there will be dumb people, but the chances of them causing injury to anyone else is still tiny compared to cars. You're missing all the times (quiet streets, quiet times of the day) when no one is around and it doesn't make sense to wait for a light (and for cars to show up that'll probably pass too close by the cyclists when the light turns green).
[1] http://www.chicagotribune.com/news/local/breaking/ct-bike-st... [2] http://www.sacbee.com/news/politics-government/capitol-alert... [3] http://www.denverpost.com/2017/01/26/senate-bill-bicyclists-...