The Wikipedia article on the tropical year gives a more accurate value for the mean number of days in a year than was previously used. It would also be more convenient to make the period of a correction a multiple of the previous period. This was a fluke for the alternating series composed of unit fractions.
As one can see this works quite well for the mean length of the year. A limit on the usefulness of any calendar and its set of rules results from the changing length of the day which decreases by about 1.5 msec per century. Using the first two fractions would probably be the best correction to make at this time. In making changes we also need to consider the convenience of decision points and the ease of transition from one set of rules to another. We have a window of opportunity to make such a change before the year 2100. The rules for the Gregorian calendar are good for approximately 3200 years and the change isn't actually necessary. It would just be a matter of convenience. Should we give the World an opportunity to decide or just let it ride?