This is comparable to project templates in GreenHopper Classic.
The creater of a new Rapid Board does not have to care about correct column / status mapping and (color) visualization, but can simply rely on one or more named templates predefined by a JIRA system admin. that saves time and avoids errors.
I see, that today you can kind of bypass this problem by using the COPY function. but this has the same disadvantages as e.g. copying normal PowerPoint files over and over again by various persons, without knowing which is the most relevant / error free one. and the alltime risk, that you copy "crap". having a central QA'd template is much more robust.
It would also be good to be able to change the template for a Rapid Board after its creation.