That's an excellent question, and I'm glad someone's asked it.
1) While the game was "abandoned", I started drafting a sex scene between Dylan and Violet (who I think is a very hot girl). When I returned to the game, I figured it would be such a waste if that scene was not finished/published.
2) I wanted to diversify the girls on the game. Don't get me wrong, I really like Vanessa, but I think we all could enjoy a new girl for 1 scene. I know I could add her in a scene with Vanessa, but I think Violet and Dylan deserved her own scene.
I do plan to add more Side Stories. For example, I have one already drafted between a younger version of Victoria and an younger version of Doug, showing the first time they got together. I even posted a poll on my patreon and, so far, all the votes are for hold on Side Stories 02 and work on Chapter 07, so that's why I'm working on Chapter 07, and Side Stories 02 is on hold.
The main reason for these Side Stories is to provide more depth, more background content to the characters. For example, I haven't decided yet how I will be showing the scenes where Vanessa cheated on her ex-boyfriend... It may be through a series of Side Stories, or some "memory" time in the regular story... Let's see...
I hope that answers your question
Cheers!