Please let us update the prospect status date to use a date in the past. It's not accurate if our gift officers forgot to update that field and when they change the status, there is no way to use a past date which would more accurately display the time in the donor cycle. It might also be helpful to include a security option on the field so that people can't just keep changing the date unless they have the security rights to do so.
I voted for your idea to be able to back-date when making the status change, but you can also go to "Show Status History" and edit the date there to be in the past.