Queens abandoning the nest? That's not what happens. When queens "abandon" the nest, as you call it, which is actually called swarming, they take 1/2 the colony with them, leaving behind the other 1/2 along with swarm cells containing the larva of virgin queens. This is a natural occurance that happens 1) when their living space becomes too crowded 2) when living conditions and area conditions highly unpreferable 3) to create a new colony.
CCD, or colony collapse disorder, which I think you may be trying to refer to, is when a whole colony of honeybees disappears for an unknown reason. Some thought to be causes are: mites, viruses such as EFB, AFB, and Nosema, and pesticides. (No, cell phone towers are not the cause. An experiment was done in Germany and they said that the cell phone towers beyond a doubt do not cause CCD.)
These workers are necessary to the hive. The total time from egg to hatching takes 24-25 days for a worker bee. Their total lifespan in summer (they stay in the hive keeping warm in winter, so these bees are raised for a different kind of work and with fat bodies to live longer) months is 8 weeks. The average honey bee produces 1/12 teaspoon (5 drops of honey!) in her lifetime. 2,000,000 flowers have to be visited to make one pound of honey, requiring a LOT of bees. Bees eat eight pounds of honey to produce one pound of beeswax. A resting worker burns .7 mg/hour, a flying worker burns 11.5 mg an hour. The colony needs this nectar to produce honey. If they eat nectar that hasn't been fully turned to honey, they will get diarrhea and the colony may collapse. Every bee is needed, and every load of nectar counts in their survival.
Source: "The Beekeeper's Handbook" the 3rd edition, by Diana Sammataro and Alphonse Avitabile