It depends on the angle and speed of the entry as well as the composition of the rock whether it burns up or not. And rocks that small are not listed as threats - again the likelihood of hitting a city are vanishingly small - Chelyabinsk got lucky.
The fact remains that our atmosphere only affords some protection from very small rocks. Angle won't make any difference in the future, just as it has never made any difference in the past -- the big ones won't burn up, and the big ones aren't all that big, but they pack as much as or more (or much more) destructive power than nuclear weapons. A rock less than a mile across delivers more energy than the simultaneous detonation of all the world's nukes.