Don't worry, sealants will not put dentists out of their jobs. First of all, sealants don't last forever and also someone has to apply the sealant onto the tooth, and there is a ton of other things aside from sealants and fillings that dentists do. As for sealants, they have been around for quite a long time and they are a part of the whole movement towards preventive dentistry. One of the reasons, in my opinion, why you were not offered sealants by your dentist might be how old your dentist is. I've heard that "Old School" dentists are known to be all about drill-n-fill as opposed to preserving tooth structure. Personally, I didn't know about sealants, and by the time I found out about them, my mouth was full of amalgam and I also learned that my insurance didn't cover them.
Hope this helps,