I say that it all comes down to time ...
Developers have had high expectations for the Wii (at best) for a touch over 1 year now; after Nintendo showed of the Wii at E3 in may of 2006. Before this, third parties believed 'da hype' and saw the PS3 as the obvious winner to this generation; the XBox 360 was considered an important console in North America for the near future. The point at which all developers would be forced to pay attention to the Wii is (more or less) just about to happen as the Wii becomes the top selling console of the generation.
So, using that timeframe we know that a lot of Wii games would have had (at best) about 1 year of development at this point in time with a large portion of Wii games having less than 6 months of development. The larger games that people notice are not that available on the Wii probably take between 18 and 30 months to develop. What this means is that most of the larger games we can expect down the road for the Wii are probably not at a point where developers feel all that comfortable showing them.
Basically, suppose that Capcom is pleased with the sales of Resident Evil 4 on the Wii (which, according to their sales projections, they should be) and decided to create a Resident Evil spin-off and a Dino-Crisis game for the Wii. These games would probably have began development right about now, we wouldn't be able to play them until mid 2008, and they wouldn't be released until Q4 2008 or Q1 2009 (at the earliest).
