Shortly after the Ionia vs Noxus Showmatch , where Guardsman Bob showed Innervating Locket's potential on Udyr, the item became very popular and was removed from the game a week later. Morello says there were plans to remove the item before the showmatch.
In V184.108.40.206, Innervating Locket was likely remade to suppress the potential supporting power of Sona.
Innervating Locket was rumored to be re-introduced in Season 2.
Several employees at GamesCom '11 also mentioned a possible re-introduction of the Innervating Locket.
Innervating Locket may also have been removed due to Champions like Udyr who possess low cooldowns on their abilities, allowing for the passive on Innervating Locket to become a source of near infinite sustain for such champions.