I find that crop consultants are more prevalent here in the south because of our heavier insect pressure.  Started back in the days when we all grew cotton, because cotton is such a difficult crop to manage and has so many insect pests.  Many folks still use them for soybeans and corn.  I have been a consultant, and there can definitely be benefits to using one.  Many times the consultants will save a farmer money by monitoring insect populations and know when, or when NOT, to spray.  I usually found it more difficult to convince a farmer not to spray than to convince him to spray.