Specialized agriculture can be looked at from both sides. The farmer would perhaps say that it is easier to specialize in just the one crop. There are less things to think about when you only have the pests and peculiarities of one plant as opposed to many. It is easier to grow one kind all in the same area, and in the same containment. No particular effort to keep them separate would have to be made, and having only one kind of seed makes it easier to keep track of what is sprouting when the plants are young.
On the other side, to grow only one variety of anything strips the land of certain nutrients. Farmers who are environmentally conscious know that it is better sometimes to leave the fields for a year, and sometimes even better to plant a compatible plant on the off season to restock the soil. While the farmer may have to work a little harder at outset, diversity could be the answer if one of the crops should have a problem. Chances are good if your stock is diverse enough you will still have something that survives.