i think its a great idea and have always planned to do this myself.
too many people feel they lose their identity when they become a couple, as though the very things that make them 'them' are no longer allowed and they now have to be 'coupleish'
a couple is two people who choose to be together, not two halves that become a whole.
i am me and always will be, no matter who my partner is.
i think one partner tends to dominate and insist the others belongings are discarded, because they 'don't go'.
this way, you can share each others beds every night, be separate if one is ill etc - but also each room can be the sole resposibilty of the owner - the girl can have whatever she is into, be it fluffy pink things or goth...and not have to have a mans stuff in there and he can have his boys toys or whatever and he will be happy
both get to keep a little piece of pure 'them' and this in turn helps prevent resentments