Having Jimi Hendrix DLC in the latest Guitar Hero is a big selling-point! Pity for Wii owners, then, that you won't be seeing it. A Blactivision PR rep has told MTV:

Due to technical or licensing restrictions, the DLC offerings will not be the same for every console platform. For example, certain artists prefer to keep the integrity of the track pack rather than releasing singles and the Wii’s infrastructure only allows us the ability to release single songs as DLC.

"Artists prefer"? Hahahaha. Hahahah. Haha. Hah. Oh. Oh man. Good one, guys. Artists. Hah. *sniff*. Oh my... ‘Guitar Hero’ Wii Not Getting Jimi Hendrix DLC Due To Wii Limitations [MTV]