When one thinks of all the pilots who have managed to kill or seriously injure themselves when their engines conked out shortly after takeoff (or anywhere else, for that matter), it's astonishing that at least a few hours of glider training are not mandatory for all private pilot ratings.
Glider pilots also develop excellent stick-and-rudder skills, and 250 glider hours can be applied towards the commercial power rating, thereby saving yourself 10K or so in rental fees. (And when your contemporaries are sweating out their power-off accuracy landings, you'll be laughing.)
There are also a fair number of jobs as ride pilots at most glider fields — a good way to build time, make a few bucks and get used to carrying pax, etc.
Most importantly, soaring is one of the purest forms of flying a pilot can enjoy.