No, it isn't necessary, but if the cabinets look dated you should consider replacing them with something that looks more modern. Oak, maple or cherry are really the only hardwoods used for cabinets, and the type of wood is a personal preference. Oak is not a bad wood in real estate.
The best way to update older cabinets is to install a new counter top preferably with solid surface one such as granite. Then add under cabinet lighting, followed by replacement of knobs/pulls.