There is, I'm sure, a place for one-shots,
but they've been abused so
 often it's
 hard to remember what that might have been.
  
 Power on reset - before the clocks have safely started. PONG, an inspired
 use
 of monostables. Watchdog timers, sync fail detectors, three shot lockouts
 .... 
 
They are also quite useful anywhere that noise from a clock would cause
problems.
Eric