Part 2:
The history really adds to it too and that's a good thing about Asagi, etc as well. It's weird to say this since sequels can be an issue in other forms of media, or just milking the franchise, but I think in the world of hentai it would be a good thing. Make the girls become iconic avatars of the series and even company, see how they grow and change and strengthen the fanbase. I don't know if we would still be talking about Inyouchuu or Asagi if they just had one or two games and that was it. On the flip side I wouldn't mind seeing some other titles get a new installment, I thought there was rumors of Kowaku no Toki 2, and they could do another goofy Hanamaru 3 still with extreme content, etc. Maybe one could argue this was an issue with Lilith and their current state, they kept coming up with so many new series, but a few sequels here and there outside of the Kagami stuff maybe could have helped them popularize more series instead. Maybe that's just me though.