If your cat is indoor/outdoor, you need all the vaccines every year. If your cat is indoor exclusive, there have been studies that link vaccines after 3-4 years of age, to the development of cancer, so I don't vaccinate my cats after this age. In some areas (Illinois is one), rabies vaccines are legally required.
If your cat goes outdoors, is around other cats who might get outside or if there is a chance of rodents (even little field mice) in the house it's a must have. My baby is strictly indoors on the second floor, but I get it for her as a precaution. It's cheap & worth it.