Interesting how they once again gave such a prominente role to a villain not that known, in the 2nd it was with The Fallen, a character that hasn't even appeared on any of the shows, in the 3rd it was Sentinel Prime, who has never been a villain before, now it's Lockdown, created in 2007 or 2009 if i'm not mistaken, in one of the tv shows used to help promote the first movie when it came out.
Weren't there other more known villains in the original Cartoon? I know that Unicron is still left to use, but besides him and Megatron isn't there anyone else that's not so recent?