Steeljaw and the Wreckers? So the redneck robots have an attack dog? What? Are they protecting their meth lab? That's the only reason people have Rottweilers down here in the south.
Yeah, the two minute trailers and the 30 second adverts are the end-all be-all of characters being in a film. That's like saying Megatron will have little to no screen-time because we've only seen him in two tv spots. So? He's still in the trailers. The only reason he's a jet is because 3 different robots with the same exact vehicle mode probably wouldn't sell well.
Or more likely, Hasbro read the script, saw the part that says "monster dog thing attacks stuff" and said "hey, we should make something like that." People expecting the Dreadhound to actually be Hatchet are likely due for disappointment.