Comic Book Resources wrote:"Transformers 2" is being prepped for 2009, as is a new cartoon series to spin off the upcoming movie.
The reason given to licensors as to why the robots look so different in the film is so that hardcore fans will stay loyal and keep buying the old toys, which they're relaunching, even if they hate the new movie.
Licensing has explicitly stated that companies doing merchandising have to avoid doing anything too similar to the original Transformers line, so as not to mix the two separate and profitable properties.
This possibility has been discussed several times on Seibertron.com's forums in the past. It has been stated that a possible reason for the radical departure of the movie robots was to protect the look and designs of the classic Transformers characters. This could also be a way to make sure that there is no confusion regarding licensing during the times that Hasbro is not sharing profits with Paramount. It was revealed at BotCon 2006 that Hasbro would be sharing profits with Paramount for an unknown period of time surrounding the release of this summer's Transformers Movie.
We will consider a lot of this as speculation until we hear something official from the powers-that-be at Hasbro.