I love using VNs to study! I would say I've made a bunch of progress playing, especially since its the medium i find myself spending the most time with. I can easily sink a few hours into playing uninterrupted, with pure books the mental fatique sets in a lot faster. I feel like, since most VNs...
Depends on what Im looking for from the game. But personally I feel that the MC having a set personality makes for more interesting storytelling, which is usually what I care more about.
I've never really played anything with gameplay so i guess i cant say for sure, but im mostly interested in the story and characters so im happy with just reading. I definitely treat the games more like immersive books.
I definitely don't mind no voice acting, I used to play a lot of mobile VNs that generally rarely had any. I agree that a good story can definitely stand on it's own! Personally, the premise, characters and story matter much more to me.