Because it wouldn't work? The only price at which scalpers would bail out is the one where scalpers make no money. In other words, Nintendo would have to raise prices to the same price as the scalpers - what has Nintendo achieved? The same people who couldn't get a console at $600 will still not be able to get a console at $600.
Scalpers are just a product of the supply/demand curves being out what. Econ 101, supply goes down with demand remaining constant, price goes up. At launch, there simply isn't a lot of supply, and demand is at it's peak. The "natural market price" of the console is much much higher than the price Nintendo sets.
Scalpers don't reduce supply, they just shift supply from a cost controlling group (Nintendo, the retail store) to a group that would charge the market price. Nintendo setting the cost to that price would not magically increase supply. All the people who struggle to get a console at launch? They'd still struggle to get it, they'd just struggle to get it from Nintendo directly (because it's out of their price range) instead of struggling to get it from a scalper.
Now, the imminent price decrease might also decrease demand at launch, which would bring that "natural market price down" - but that would either suppress demand permanently (as the system fails to take hold) thus damaging the product, or simply shift demand to later in the cycle, where the scalpers would step in and the process would resume.
Practically speaking, Nintendo could never get retailers to do it. Retailers won't fork out the 600 asking price for the stock at launch, and if they do, they won't accept a giant 30% markdown on their existing stock. So this kind of manipulation isn't possible unless you (like, say, Apple) own the retail front end as well.
