They actually do add content, but very little of it is implemented in the actual game outside of debug mod (a lot of it isn't even in the debug room). The one thing that people don't get is that the version we have access to and the version the dev himself is using are two very different games altogether (his own is probably more or less already complete). For example if you use RPG maker to edit the transition cutscene from act 3 to act 4 along with some map editing you can actually access act 4. Act 4 has a lot of new stuff and with some editing it is entirely possible to play trough the main story to the end (all the common events/scripts and maps bar few are already there) and even see a good chunk of the new content, but the catch here is that some key maps are missing from this version of the game (like Romasha's act 4 room, act 4 command room, etc.), along with most events not calling the right common events or entirely wrong scripts at the wrong time which is really tough to fix. Also check the spine files, there is a lot of stuff that isn't used even in the debug room events.
I put together a somewhat working version of act 4 for my own use (and no i will not be uploading my own files here for people to try it for various reasons), but had to fix, remake or just reinvent a lot of stuff just based on a hunch alone as to how the dev intended it to be only to come to a very simple conclusion: I shouldn't even bother with it and should just wait for the full game to hit release and enjoy it the way the dev intended to instead of wasting my time fixing something inherently incomplete (act 4 is event/script wise a total clusterfuck), so in that regard i actually agree with you.
Also having said all of the above and having seen a lot of what act 4 is going to feature i will just say that it alone is worth the wait even if people didn't like the content that came before it. The really good stuff starts at that point in the game (lots of group sex, orgies and such along with plenty of opportunities to finally get Romasha fucked up and turn her into a total slut), of course if the dev actually implements all of that in the end because at this point of time he is actually adding even more content and seriously approaching feature creep territory (right now he is in a "you know what would be cool" mode of work) so yeah he might get himself stuck in a corner with all the bugs (i have zero idea how he is going to go about testing and fixing all of that and how many beta testers is he going to actually need), so we might see him cutting content off for the final release (either him or that other guy that is working on programing).
