Jimi Hendrix won't be gracing additional tracks on Wii due to Nintendo's online content limitations.
Guitar Hero: World Tour offers the chance to download additional Jimi Hendrix tunes onto the system as part of a "track pack", essentially a bundle of songs that must be downloaded as a complete set, instead of individual singles.
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.Activision Blizzard rep speaking to MTV Multiplayer.
Although the Wii is able to receive downloaded content, Nintendo doesn't allow "duplicate content" on the Wii store, and as licensing issues restrict downloads as singles there won't be any additional Hendrix for Wii owners.