Classical Period Interiors: Why?

Are period interiors out of date? - there are arguments against classical design on every level.  But if one is going to create a house inspired by a specific historic style, then the interiors to some degree should match the period style of the exterior.  Is this a steadfast 'rule'?
I would like to open the first discussion on Classical Interiors posing these two questions:  Should we be even designing houses based on historical precedent and if so, should the interiors match the period in some way?