Well, supporting this doesn't really need to be forced. Any game that supports single-screen/gamepad-only play will probably support this by default.
Also anyone who thinks Nintendo will pack in Wiimotes is insane. There are already hundreds of millions of them out there and, statistically speaking, it's safe to say most future Wii U owners will likely have owned a Wii. No business is going to waste money on a pack in unless they feel it absolutely needs it. If they can avoid packing it in without being an inconvenience to most customers, then you can bet they won't include it.
Packing it in makes no financial sense if there is a high rate of redundancy, and lets face it, they would rather sell controllers than give them away. They might include it in a marked-up "premium" bundle but it definitely won't be standard.
Lots of people have Wiimotes, but the number of people with Wiimote Pluses is much smaller.