I had thought about de-racking mine too, but I find them useful to reach the top of the car. I just put one foot on top of a rear tire or on a rim spoke and use the rack to pull myself up! Very handy. Other than that, I have no use for them either.
I think most people on this MSG Board who do not have the Roof Racks are those that did not select the option that provides the racks. As far as adding afterwards, I was told when I checked on buying the OEM Racks from the Nissan Parts counter at my dealer, the parts manager stated that they are not offered and that even if they were you would need a Murano that was built from the Factory to handle them. Apparently they require extra Reinforcement in the roof. I don't know if this is true but the Parts guy seemed sincere.
I see... so I probably don't want to de-rack my Mo just because...
It's funny, I spent this morning polishing the Murano (Zaino!) and I kept instinctively reaching for my roof rack as I stepped up on my step ladder... Figures that as soon as I post this, I find a use for the rack!
Still, if someone finds instructions on how to do this, I might still be interested if its as easy as taking out a bolt and then bolting them back on if you need to... something tells me it isn't that easy, though!