You also have to realize that this is a porn game, story or not. The better choice to keep the most people interested in the game's content is to flesh it out with an even spread of these scenes to hit as many interests as possible. I would not call Ravager a game with porn, it is most definitely a porn game, however good its story ends up being. As such, it makes sense for them to have the priorities they're currently displaying, making sure every possible character has content instead of just running with one or two 'main' characters and then adding more in later. This isn't some mainstream indie game they're trying to pack up and ship in a timely manner, and we shouldn't expect it to operate on the same timeline or priorities.
There's also another problem with developing as you've stated, and it's how Ravager's staff crew is set up. Each character has their own writer, and rushing the game forward while only working on a few characters doesn't make those characters go any faster, it just means all the other writers get to sit and twiddle their thumbs. Ravager is more styled as a large collaborative project than other games like it usually are, so there'd be no real point to making half the staff do nothing.