We’re talking about the crease lines that are deliberately pressed down the center of the front and back of both men and women’s pants. Today’s commercial equipment provide perfectly even creases when laid on a press correctly, which you can’t get at home because you iron half of a leg at a time.
Some people have an irrational dislike for center creases in their pants. Some iron them out immediately when a new pair comes into their wardrobe. Some also instruct their cleaners to please not put center creases in. What it really comes down to is that for business attire you will feel more polished and confident wearing creases, especially so if the pants have pleats. It also has been talked about in the fashion world that it elongates your legs. When you are wearing pants for a casual occasion, with flat fronts, it is perfectly acceptable to have your pants pressed flat with no center crease in the legs.
There are always exceptions to the status quo and that are the specific women’s styles like Palazzo pants, or a knit or sheer fabric that has more of a flow to them that would compromise their look and style with center creases.
No matter what your personal decision, we can tell you that your pants will look better pressed whether you decide you like the crease look or not.