The problem is that a simple patch issued is not enough to make already released games work with the Natal. Developers would have to write some significant code in order for their games to be Natal compatible. It may be safe to assume that developers will not see this as a worthwhile endeavor given the time any money it will cost to write the code.
Is this a big deal to anyone? I have no interest playing already released games Natal style and think games created specifically for it will be the most entertaining.