Monitoring will tell you how well the baby is tolerating labor. It can help you diagnose a problem you might not have any other way of knowing about like an occult cord prolapse. It can help you make informed decisions about transferring or seeking additional help. Knowing that baby is not stressed by getting reassuring FHTs can help calm you if your labor is dragging and you're starting to question if things are normal. Not having any way to check in on the baby can cause unneeded stress during your labor.
All of that said, I haven't checked FHTs during any of my 5 UCs. My first baby, I was kind of just flying by the seat of my pants and didn't think much about learning how to check. My other births have been fast and straightforward, and I haven't felt the need to check but I personally wouldn't go into labor without having a way to listen.