The modern aero deep dish rims that use 20 spokes (or less) are plenty strong with a low spoke count. But look at those massive (and heavy) rims. The rims are incredible for brute strength and stiffness and simply require less spokes. Now, resistance to rim cracking and longevity seem to be a problem in my shop compared to traditional wheels; so there is a trade-off there.
As for breaking spokes: Properly selected components for intended use and properly built wheels don't break spokes in normal use. They can, with advancing years, but the rims usually wear out first, from my experience. For racing and fun you can always cheat the odds and go a little lighter, but durability suffers.
Yours in Cycling,
North Road Bicycle Imports P.O. Box 840 166 Courthouse Square Yanceyville NC 27379 email@example.com or firstname.lastname@example.org Local: 919-828-8999 or Toll free Nationwide 800-321-5511