Hello,
Jeniffer isn't here when I start a new game but i get an event were she gave me the serum. It's normal or ... ?
It's completely normal and happens in every play through. It's just free stuff and has nothing to do with her story.
#1 is fine, but #2 is very subjective. If a dev subjectively thinks a feature does not "mesh well" and I subjectively think it does, wouldn't it make more sense to leave it in the game so that I can choose to use it and they can choose to not use it?
There isn't just "one dev" here. There have been numerous people who have put work into this project. The majority have simply added a couple things and vanished for whatever reason. There are actually several things within the game that don't really make sense. One of them being the "talk with employees" option in the main lobby which used to be super useful to the point it felt like cheating, but now it feels like a waste of time.
From my experience, Trist doesn't seem to remove anything, even if it's old and outdated, in fact, he may even update it to at least make it functional, even if it becomes pointless. If the option was removed, I'd bet that something broke it and fixing it was simply too much work for something he didn't even create and the majority never used.