I disagree - I believe people have an intimate enough relationship with certain meetup groups that they work as a micro-social network. To that end, it would make logical sense to have an independent application for those groups.
With that said, this strategy would not be an alternative to having a central Meetup.com application - this strategy would work in conjunction primarily to leverage the additional app store SEO boost from having thousands of unique titles. Each individual application would link right back to Meetup.com's primary application and people would have to sign up for a Meetup.com account in order to use it.
With that said, there are shortcomings to this approach. This empowers group organizers a little more than Meetup.com would ideally like and might work better for companies that white-label their services.
I still don't doubt that it will greatly increase raw traffic numbers - but maybe thats not what their priority is at the moment.