The way I kind of see it, with the main bread and butter being the simpler toys, Hasbro can make a higher profit off of them as they are simpler to design and make. So they therefore can make more money off of them as although the RRP might be a little cheaper, they cost less in design time/resources.
While the movies have an M rating, that kind of adds a bit of edge to the movie. If the movie were rated PG, it would be less appealing to the older movie goers. The M rating doesn't stop younger viewers going to it, and makes the film seem more 'edgy' (? ) to everyone else. In a way, the name alone of the movies gives a bit of oomph to the toy side of things.
I think the appeal of Generations line for collectors and pre-teen is admitting that pre-teen to teens to collectors will want something a bit more complex than the bright coloured simple toys. While the Combiner wars hasn't got much in the way of media support to get the advertising out there, a cool looking robot that transforms into a cool vehicle and THEN combines to make a big robot is enough to nab the eye of an errant kid that is not interested in buying a one step changer.
The generations line is essentially trying to be two things. It is trying to tickle our G1 Nostalgia, as well as provide younger kids with a bunch of cool toys.
Sure they might not know who Superion is, but back in the days of G1 Superion and the Aerialbots were new characters as well. When I was a kid, I bought Transformers because they looked cool and were fun to play with, not because of nostalgia. Hopefully the Generations can provide us with nostalgia, as well as giving young-uns newly discovered characters that are cool.