Hi there,
Yes, You'll have full control over every scene, and if that's your choice, you can avoid certain sequences entirely, though you may miss out a lot of content.
The MC isn't dumb, though she may be a bit naive and too trusting at times but she learns and becomes more mature, unless you want her to be dumb and play it that way.. therefore the scenes were tried to carry a depth and meaning and not be fake or just a fap fest.
Your decisions will influence how the story unfolds.
To answer your question, yes it's optional.