Obviously the toy line did not work that well despite the financial success of the movie.
I know you are a fan of the Bay films but keep in mind that they don't seem to be made with enduring appeal in mind. It is basically a 'get a thrill and forget' sort of deal as there isn't anything in them that is particularly memorable to the typical audience. It's not like Die Hard, Star Wars or another movie which is spoken about for years, decades after. The general populace appears to have forgotten about it after the end of it's theatrical run.
The 'Thrill and forget' audience which has made them their billion dollar Box office smasher are not going to care much about the toys to begin with and are more likely to forget about the movie as soon as it's Cinema run is over. At most they will buy the Bluray/DVD release when it comes out.