1. A different set of people (although I'm sure overlapping) are reading those two comics you're talking about, and with different expectations. I certainly don't usually read manga about bullying (Takagi-san is about the limit of my tolerance, and most would agree that's teasing much moreso than bullying). But I do read manga about cute fantasy creatures. That is to say, you most likely won't find me complaining about stuff in whatever manga you're talking about because I would never get anywhere near it.
2. Compared to some other manga, this one seems to somehow lack self-awareness that the protagonist is being abusive; in a way the sugar-coated bullying is much more alarming because it seems to say to the reader, "Bullying is just fun and games kids ^^"—which is, well, a bit disturbing. By contrast, in weird fetish mangas or whatever you're talking about, there is more often an implicit understanding between the author and audience that what's going on is not really okay, or at the very least not socially accepted (but that the author/audience enjoy it regardless, often as a guilty pleasure).