There are various flaws in your critiques, Urbs.
1)Nintendo was the only console giant to make a ton of money last generation (many at the time labeled the big N as a profitable third). They weren't making sales, but they were making money. If the Wii failed, Nintendo would have been able to cover it. Epic currently is in a bit of a monetary rut. UT3 isnt doing all that well, and Gears AFAIK hasn't been selling that much passed its initial boom upon release. Epic has a lot more to lose if they take a risk.
2) Aside from Mario, platformers don't seem to be doing that well on the Wii. Some do marginally well, but their sales tend to be more based off of name recognition (Sonic, Crash, and Spyro are still ever so slightly relevant enough to get decent sales) or based off of a movie. The genre itself is in a bit of a rut, and aside from heavy hitters (Mario, Ratchet, more than likely Banjo) platformers don't perform amazingly well on the market. That doesn't exactly bode well for Epic. Also, while I do prefer platformers on the wii they tend to have hard to manage cameras, and rarely make good use of the motion controls (the sole exception being Crash of the Titans, and even then its really only used to pull off special moves). if there was a game made with the Wii in mind, it was Zak and Wiki. Jazz however would play essentially the same on any system.
3)The Wii has done well. Nintendo games have done well. Third party games, however, have not exactly done well. Those third parties that do tend to fill the system with Shovelware (See: Ubisoft. For every good game like RRR they have about 5 terrible ones like GT Pro series.) Again, for a company that is in a bit of a financial bind, this isn't a good option. The PS2 would be a better choice than the Wii tbh.
Just remembered that Epic gets tons of money by licensing its engine forget the above.
4)Jazz Jackrabbit 2 is the most cliched platformer ever made. The character is not this bastion of originality that you make it out to be. Cliffy B might as well just rolled a katamari over other popular platformers at that time and called it JJ2. From the movesets, to the scenery JJ2 is essentially various platformers rolled into one coherent whole. The most innovative aspect about it (the online multiplayer) is essentially UT2d. The thing is however, JJ2 is extremely well done. Thats what Epic does. They make games that are cliched, but very, very well done so you really don't care that the character hovers like Earthworm Jim or that the game takes place in a dystopian future.
5) For some reason Epic only wants to use one house engine at a time. Their current engine does not work on the Wii unless they considerably cut it down. Epic has previously stated that it does not want to spend the time fiddling with that as it could end up being more work than its worth.