With that ending, I think it's pretty clear who's going to be the top in this relationship, lol!! Overall a very nice story with a fitting - and actually quite cheeky - ending. I don't know what other commenters are thinking but
Tsubosaki straight up calling Kazuki by her name without any honorifics pretty much confirms that, barring any objection by Kaz (which seems highly unlikely), they're going to be in a full on dating relationship by April.
So since the relationship is pretty much confirmed and all that was missing was explicit physical expression, I would strongly disagree that the story was "not worth reading". I would certainly have liked to have seen a bit more too but I'm not too surprised at the ending given the overall gentle tone of the story.