I know, "Curb radii?!" You must be wondering why I've decided to put you to sleep, but hear me out.
First I have to explain what a curb radius is. Imagine the corner of a block. It's rounded, but imagine it were a right angle with each curb extending to a point of intersection. Now hold the location of that point in your mind and visualize the real rounded corner. The curb radius is the distance from that imaginary point to the point at which the curb starts to curve. Got it? Here's a picture (it's the distance from B to A):
This is important because large curb radii mean cars can take the turn faster and pedestrians have farther to cross in an intersection. Therefore, large curb radii and the gradual curves they imply are bad for pedestrian safety and convenience.
The shorter the curb radius, the sharper the turn, and the more cars have to slow down and pay attention when they turn. So, support small curb radii!