My understanding of Gavin's motive is that the hard fork is purely ego driven. There's no urgency to change block size. He just wants to be dramatic and make his personal mark on it. But controversy, technical-wise, is that some Bitcoin users may have their coins lose compatibility with the new implementation. In a sense, it may be Gavin and Hearn's attempt to hijack the Bitcoin name and implement their own coin or make changes to the protocol.