An excellent topic. I learned the hard way that when you are in competitive situations, you are playing to win. This means that your decision regarding whether to run out or to duck must be based on a REALISTIC assessment of the odds that you will run out from where you're at. If you are losing too many games as the results of failed run outs, then obviously your assessment has been faulty. Further, excellence in pool requires that you play within YOUR capabilities and in accordance the conditions that YOU are facing at any given time. Granted, we see the pros play runout, runout, runout when they play 8-ball, but they are the best in the world, and they're playing on 9-foot tables where there's more room to maneuver. 8-ball on a 7-foot table is an infinitely more defensive game simply because the congestion makes runouts much more difficult.
Finally, pool is about much more than putting balls into pockets one after the other. Other skills, such as safety play, adjusting to the equipment, managing the table, and outmoving your opponent are all part of "being good".
If you want to improve your runout ability, work on it in practice and friendly games. In competitive situations, however, particularly in league play where you have a responsibility to your teammates as well as yourself, I would strongly advise you to play the percentages and play to win.