No clue what your talking about. 0.4 almost doubled the content in the game. 1200+ renders and 88 animations.
Did you play 0.1, 0.2, 0.3 separately before playing 0.4? if not how'd you know where the previous ends and where the next starts. have you gone through all the scenes, all paths, all variations? in those scenes with big sis, were they just 2-3 images with 100 lines of dialogue or were there a good number of renders and animations in each of them. Just compare the CGs and animations of 0.3 and 0.4.
I have a brain, but I can't see it. Doesn't mean it ain't there.
If you are going just by the no. of sex scenes (anal, vaginal) then yes not much has been added. Those will be added in due time.
It's still just 0.4 of the game. But 2000+ renders and 160+ animations, and just 3-4 actual sex scenes, that means there's more story and not just click and bang. Upto 0.4 it was mainly character development and story progression. The next few updates should add more sex scenes than the previous ones.
If you don't wanna be disappointed, i suggest you play it when it is completed, which I estimate would be near the end of 2019 at this rate.