Cannot create a fixed annual membership type with no rollover date

When creating a new membership type, if the period of the membership is, for example, one month, then there is an option to set a rollover day, but it is not a required field. If the period is set at, for example, one year, then the user can set a start date and a rollover date, but the rollover date field appears to be a required field, so it is not possible create an annual membership without setting a rollover date. The user should be able to create a membership type without setting a rollover date.

If the default dates are accepted (i.e. start date Jan 1 and rollover date Dec 31) then a user signing up for membership on Dec 31 gets a membership that runs until Dec 31 the following year, i.e. they get a full year of membership, but if they sign up on Dec 30 they get just one day of membership. This is inconsistent with a use case where the membership type should have no rollover date.

Example: an organisation offers fixed annual membership, with membership fees changing quarterly depending on when in the membership year the new member signs up. So if the fee was reduced by 75% for new members signing up during the last quarter of the year, this should apply consistently to all dates in that final quarter, including the final day of the year. By providing a facility where the rollover date is not required this use case would be satisfied.