That is one of the most ridiculous generalizations I've read in a long time. I want you to think of every manga you've ever read. Are you thinking of them? Good. Now, every manga that includes scenes of people changing clothes, showering, or bathing should be tagged as pornographic according to your comment. That's a staggeringly large amount, isn't it? Then of course you also have to think about babies being changed or bathed. The transitive property does not work in these situations (i.e. All porn has naked people, thus anything with naked people is porn). Next you're going to suggest that gore is all about blood, so anything with blood should be tagged as gore. All those poor romcoms where the MC gets a nosebleed seeing sexy situations are now gore. That's why MangaDex has defined in the
Site Rules what should be in each category in the Title Metadata segment:
"2.2.2 The content rating for a series is based on the highest level of sexual content in the series. In general, entries that focus on sex or contain uncensored sex scenes should be marked as pornographic, entries with heavily censored or non-explicit sex as erotica, and entries with light exposure as suggestive."
Which means that unless something seriously changes in the future raws (which I haven't looked at), this should probably be suggestive or erotica at worst. Now, I'm sure there are some 'side' illustrations the author has done that probably depicts some rather explicit situations, but if they aren't part of the actual story, it's easy enough to just not include/separate them. Meh, whatever, if I lose easy access to what was a mostly cute manga it won't be the worst thing.
Side note: Doing a bit of investigating (noticing all the threads for much further ahead chaps down below), it seems that it might be the fact that the Spanish translation of this series has included a bunch of those 'side' Fanbox illustrations, so that's probably why it got the tag change.