A polar orbit does provide a better coverage than equatorial orbits. From Vandenberg AFB, polar orbits are achieved by first launching out over the Pacific Ocean and then doing a "dog-leg" turn to the right into a 88 degree inclination (90 degrees would place the satellite's orbit directly over the poles. The inclination is calculated to provide the coverage required by the mission.) The turn is done so that the rocket does not fly directly over Locpoc, California!
Polar orbits are still used by some "spy" satellites in order to provide good coverage. The JPSS orbit is probably high enough to prevent atmospheric friction, which would eventually decay the orbit into reentry. Synchronous orbits (the ones that seem to hover over a particular spot on the earth) are launched from the Cape and go into high altitude orbits. The Vela satellites, for instance, were parked in synchronous orbits for detecting nuclear explosions in the atmosphere.
Most weather radar is still provided by ground stations, but have gaps in the coverage due to not having enough ground radar stations.
Here is the JPSS website:
http://www.jpss.noaa.gov/
