It's as niche a thing over there as any "perversion." I mean, yeah, they make tons of it - they make tons of comics and about chicks with colossal cocks, too, but that's not "normal." See, kids weren't really all that hepped about Transformers a year or two back (not really sure if the success of the movie has changed that or not, but one can hope). Galaxy Force had ended on a total fizzle - Menasor, Quickmix and maybe a few others weren't actually *released in toy shops* over there, they line was doing so poorly. And those are characters that were *in the show.* So TakaraTomy basically turned to a sub-group of people that they *knew* they could sell to - these older, creepier male collectors.
As for taking issue with it... well, I think most people would take issue with female characters drawn to appear underage being thrust into situations that evoke violent sexual acts. It's just that it normally remains that niche thing that they don't have to deal with, and then suddenly... it's the main Transformers line in Japan for a year-and-a-half. It being done by a toy company is certainly WORSE, but it's not a particularly nice thing in the first place. I certainly find the story absolutely *fascinating* myself, but I don't find *any* humour in the concept.
What's *particularly* interesting is the way that Teletraan Go! Go! and Kiss Players Position are essentially devoid of the whole "HUR HUR RAPE" thingie. There's a bit of
moe, but that's a different animal that doesn't involve slobbering penis-tentacles. But they're all done by the same guy who also did Kiss Players (Yuki Oshima), so it makes you wonder who was poking him with a stick and saying "More strategic nudity!"