I think their decisions make sense for the most part. They did a lot of experimentation, and have found their femdom titles tend to sell the best.
I believe they credit their success and loyal playerbase to L Buffer's artwork and dot animations. They're right to do so, L Buffer's some sort of animation genius.
He can't take all the credit though. The chosen settings Dieselmine roll with are pretty unique, and tend to be done to the best of their ability.
It's just a bit of a shame they've chosen not to translate them, I rather enjoyed the fan translated Cornelica's plot.
Femdom is where it's at right now. MGQ created a huge fanbase for Succubus stuff specifically. I've noticed on Japanese DLsite that the better Femdom/Succubus related content tends to get between 5000 to 6000 sales, some stuff does even better than that. Most of Dieselmine's Femdom stuff all has around 6000 purchases, Cornelica has nearly 8500.
You can see the evolution of Dieselmine's thought process based upon their sales trends. In the beginning and for many years, they had rather middling sales between 500 and 2500, it wasn't until they started making monster girl reverse rape content that they broke 5000 in sales, then immediately after, they returned to the pedestrian sales of regular rape games. Cornelica seems like it really was the turning point, because ever since that mashup of animation and cg from various popular artists in the genre, they've mostly been doing the same thing.
I think Dieselmine's game have been pretty high quality, although they are much, much shorter than regular H-rpgs. Still, its a formula that seems to have worked, and Dieselmine has a very quick turnaround time for their next game as opposed to some devs who literally take years to apply what they've learned into their next game.
I wouldn't be surprised if Dieselmine is one of the highest grossing studios on DLsite based on their evolution and design model. the MGQ franchise may have many more sales per game, but they release games so much less frequently.
I think this game will do at least as well as their usual femdom fare, but i have a feeling that by the time they release their next game, this may be up there with Cornelica.