I would dispute this point, depending upon what one wants from a cruise. Consider the alternatives to OBC:
1. The House Select beverage package of wine & beer by the glass with meals (no martinis during happy hour; no choosing your bottle of wine with dinner); or
2. Shore excursions. Granted, one can achieve nearly double value by choosing the shore excursions (as many of our astute contributors have pointed out), but that assumes one actually enjoys ship's excursions on a bus with a gaggle of new BFFs. Sorry but, for many of us, that's anathema.
OBC works perfectly for those who make full use of Happy Hours at Martinis and Horizons, and who prefer to choose a nice bottle of wine with dinner. And if we want a beer or glass of wine with lunch, we can pay for that with OBC, too.
Chacun à son goût.