To sell toys

To understand Transformers fiction, it is important to understand that it exists to sell toys. Hasbro and TakaraTomy are toy companies, and they are primarily interested in continuing to sell toys to children and adults. The cartoons, comic books, etc., mostly exist to make this happen. To be sure, they normally make a profit in their own right, but this is regarded as mere gravy.

The "to sell toys" effect often distorts the fiction in interesting ways. Primarily, since you can't usually sell someone the same toy twice, HasTak constantly introduces new toys, and often requires the creators of the fiction to introduce the new characters into ongoing storylines. Older characters (whose toys are no longer being sold) are shoved aside to make room. Blatant examples include:


 * The Transformers: The Movie: Numerous main characters were killed or changed, including Optimus Prime and Megatron. A slew of new characters were introduced, including Hot Rod and Cyclonus.
 * The Underbase Saga: A super-powerful Starscream killed literally dozens of characters, with the survivors coming mostly from the Pretender, Headmaster, and Targetmaster ranks, those being the then-current toy lines.
 * Many issues of the Marvel comic had cover blurbs in the form "Introducing the Novabots!", where "Novabots" was whatever the latest line of toys was. Sometimes the storyline had to jump through hoops to explain these new characters.  (In particular, for both the simultaneous introduction of the Aerialbots and Stunticons, and the introduction of the Pretenders, there was a lot of rigamarole involved in explaining why both the Autobots and the Decepticons had new members with identical gimmicks at the same time.)  Other times, the characters were simply there, with no explanation for why we'd never seen them before.
 * Other Voices/Coming of the Fuzors: At the end of season 1 of Beast Wars and the beginning of season 2, a few minor characters were killed off, two new Fuzor characters were introduced, and many of the main characters got a Transmetal upgrade (i.e., got new toys). Note, however, that due to the expense of creating CGI animation models at the time, the Beast Era TV shows were somewhat more immune to HasTak-driven changes in characters than the G1 cartoon and comic.

There's also an interesting exception: The Dreamwave and IDW comics. The two recent holders of the license to publish Transformers comic books sometimes produce comics using whichever toy line is current (e.g., Dreamwave's Armada comic or IDW's 2007 movie tie-ins), and sometimes publish comics using whatever characters they please (e.g., The War Within and Escalation). The characters in their "discretionary" comics are often not currently available in toy form (Hardhead, a current character in IDW's G1 continuity, has not had a toy in 20 years), and sometimes are drawn with bodies that have never been toys (most of the War Within characters). While the details of the licenses these companies received from Hasbro are not available to use, they apparently require the licensee to produce some comics "to sell toys", while also allowing them to do other comics with carte blanche.