Nintendo is not in a position to crack down on third parties. Right now third parties are bailing on the Wii. The big guys are turning from Nintendo as they see their games failing to shift millions of units.
If Nintendo were to crack down on UbiSoft for example it could be disasterous. UbiSoft is one of Nintendo's biggest supporters they supported DS at launch they supported Wii at launch, their supporting 3DS at launch. If Nintendo pissed them off they could ditch Nintendo and go to work on competitors consoles, so we need to put up with their crap. EA you mention, Nintendo doesn't want to piss of EA either. Look at what happened to Sega when they pissed off EA.
Fact is Nintendo can't really crack down on any of the big publishers or they could face backlash and loose both the bad shitty games as well as the few really good games. But what about smaller developers? Nintendo can't crack down on smaller developers either. Why? Smaller developers are the future you never know which smaller developer could turn out the next big hit. Also by stiffaling smaller developers Nintendo would be killing creativity and many of these small developers couldn't afford to continue developing for Nintendo platforms.
In the end Nintendo needs to find a sweet spot. They can't crack down like they did with SNES, but they can't let quality go mad like Atari did with 2600. Nintendo needs to set standards not to high that they would offend and neglect third parties but high enough to keep consumers happy.
Example Rudolf the Red nosed Reindeer by High Voltage should not have been allowed. But Ghost Recon by UbiSoft while l0ooking shitty should still have been permitted. Nintendo just needs to create some kind of quality control.