I think someone has suggested this before, but maybe futuristic/fantasy combat is more palatable to some parents because it's more obviously not real.
Oh, god, Martin, I hope the majority of people aren't that sissy. There is nothing like the hypocrasy of fools, soothed by euphemisms.
Seriously, I'd wager Playmobil is leaning toward fantasy because the designers perceive that's what is popular. Or, they believe the knight theme needs rejuvenation, and they have made the decision that the fantasy element, in line with fantasy fiction and video games, will draw more children than the historical realism.
I like the look of the new dragons, even if the theme itself strikes me as a little dopey. Playmobil excels at imitating things. When it imitates realism, it looks great. When it imitates other people's fantasy or science fiction worlds, it looks less inspired.