This would be enormously helpful for us. We use attributes for so many things - e.g., the year a politician was elected; the year a teacher began at a school. The date field is more or less wasted in a case like this when we do not have an exact date, but we do have a year.
This feature would also be enormously helpful for my org, as we track diagnosis and referrral dates which are sometimes only a month and a year.