All answers will be pure speculation unless Ubi comes out and says something.
They might have decided that they didn't have enough resources to develop both an HD and a Wii version concurrently. So they put off polishing up the Wii project to get the HD one polished up and out the door on time.
Or maybe, as you say, the Wii version is an afterthought which was started after the HD versions were already well underway.
Perhaps the third-rate team doing the Wii version was producing a project so sub-par that they felt they had to delay the Wii version so it wouldn't damage the image of HAWX and the Tom Clancy brand.
I should add that I'm glad it's coming out for Wii at all and I hope Ubisoft delivers a quality product with that extra year.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
