I wonder if this might be due to the game's mechanics insofar as you / the MC has to make a decision as to whether you want to pursue sexual relationships w/ different NPCs. This then sets a flag that kinda branches the gameplay.
That might be easier to program (for this here way of releasing a game piecemeal update-by-update) than you as the MC actively trying to approach someone (because that means all content would have to be available right). This however would require you to have all content available already at the time of playing.
This game mechanic basically exists in all of these games, witness MILFY City, F.I.L.F., Melody, Life etc. just to name a few.
curious that you mentioned milfy city, where you are way younger and still go way out into the risky zone just to get some pussy, while in DMD the MC is financially and emotionally stable but still acts like he has to thank god if he gets pussy.
also, don't use Melody as a comparison, it's made from the same person who's making DMD so ofc it has the same style and writing.
About difficulty of programming, consider that if the author wanted to have a more dominant MC he would just had to render different scenes and have his writer/s put down different lines of dialogues; It's really nothing beyond what he already does. Having a MC acting like this is a merely artistic choice, made long ago (defining a character is something done very early, even if his backgrounds and personality get disclosed completely only a bit each time). You don't need to have all the content ready, because if you want your DMD story to work, she has to consent, otherwise I think she would prefer to go back to her mother, that at least wouldn't abuse her.
Overall, I like how the main plot developed, but I cannot stand the "female always proposes -> mc is thankful/am I dreaming -> orgasm" way to do things. I mean, it could be ok at the beginning, but now I think there should be some confidence built up in every character, not just D.
On a closing note, I doubt that D will lose any Vcard in this release. probably it will happen with that small girl that helped us to track D down. Honestly, Georgina and that girl coming back feels like a filler while watching an anime. Still, this last part is only my opinion, with very small proof behind it, so if I'm wrong, great.