Pretty sure they just didn't want to do a repeat of the Wii where they clearly underpriced their console relative to the demand. Based on secondary market resell longevity, and supply shortages almost reaching into the third year of production, they easily could have charged $299 MSRP upon launch. That's a lot of lost revenue that essentially went straight into the hands of hardware flippers.
What it means in the short term is that secondary market prices on the 3DS most likely won't be as crazy as they were for the Wii unless they managed to underprice their hardware again. Price premiums over retail on Ebay are modest at best if that's any indicator.
Longer term, it gives them a huge amount of space for retail price cuts or bundles to maintain consumer interest in the platform.
