the most terrifying thing about her boobs is that the other girl on the cover looks even bigger. like wtf, the first girl has each boob bigger than her head, how will the new girl even move?
For how much I like ecchi/smut/harem stories and I like them big... the more I see that girls the more I hear the term "jailbait" resonate in my head plus they are too big... c'mon they are naturally used as lolis with big breasts for capture perverts.
Guess this series is a case of supply and demand and targeting a niche market. Even if only a couple of percent of otaku in Japan are into big-ass knockers, if most of them buy your series due to a lack of similar stuff in circulation then it can still be a beneficial decision to put them in, even if you alienate some readers in the process.
Or it might just be the author's personal fetish compelling him to enlighten the world by showing us the one truth, Allah ackbar!