True, them and ONEONE1. But at the same time I get it, don't fix what ain't broken. Let the money printer keep printing money. The art and voice acting alone keep people coming back. Why risk trying something new when there's a chance it flops like they tried with Sex Knight Cynthia which is one of their less bought products.
Y'do realize that Cynthia is one of their oldest games ever and one of the ones that started the trend of cum collecting RPGs, right?
It also flopped because the publisher that localized it released a terribly buggy mess, during the winter holidays, and then didn't fix it for a long time, because of aforementioned holidays, which was obviously a disaster.
As for this game... I can honestly say, as someone who's tried every single one of Acerola's games that have been translated (and a number that haven't been), that Monica's game is the most innovative at its time for their NTR games series. It was the first time they actually allowed one of these games to have the "debt" be beaten without the girl slutting up at all on the first playthrough. In all their previous NTR games, it was mathematically impossible, unless you cheated. Also the first time they added even a sliver of real gameplay via the adventuring stuff.
There's a number of things, and they might not seem big... but there's a reason why Monica was, at the time, their best selling game of the NTR games by a WIDE margin.
Acerola might not rock the boat much, but they do try things out in various ways, to varying degrees of success. Sadly, whenever they DO rock the boat a lot, like with the Tear game or the Thief game, their sales tend to drop, so no one can blame them for not trying much when their fans don't want them too.