No, sandbox and free roam just sucks ass and there is really very little good reason for ever implementing it when adding choices is just so much easier. And 100% of the time...it's added to mask a lack of content. By the time it's been designed, made, images created, tested...you could be another 400 renders into the story.
There's a difference between a true sandbox (something like Lab Rats 2 or Hentai High School), and a game like this, Milfy City, Treasure of Nadia, etc., where you can click around to any of the game's locations but only find something to do in one of them (or at least, one per scripted character). Sandbox doesn't suck ass, the false illusion of a sandbox is what sucks. If you can go to a bunch of different places and do interesting things in each of those places, then that's great. If you're just going to all the places to find out which one has the next scripted event, then yes, by all means make it a VN.
It already is a visual novel heh...part of the point. Some folk want to try and make a 'game' out a VN. Even with what you describe, having a map with pre-defined locations that have pre-defined content...why? Seriously, why? Just to make it 'more interesting'? So much work, creating assets, testing...you're making a VN...just a waste of time.
