Crates are essential for safety for Scotties up to 2 years old because they chew things, and unless you are in the room with eyes on them, every single minute, they can and will chew lamp cords, furniture, shoes, eyeglasses, purses, remote controls, Christmas decorations, books, magazines, mail, door frames, outdoor decks or wooden furniture. I tell you this from personal experience. A quick trip to the bathroom for you can result in a serious injury, death, or just annoying expense. Scotties also climb on top of things, to reach something of interest to them, or to get a better view of something outside. Sometimes items you think are safely out of reach, turn out to be within their reach.
Another important reason to crate train is this: If a dog is accustomed to being his his crate and it is cozy and has good visibility and he gets treats or food every time he goes in it, it is a happy place for when you have company, or if the other dog is sick or injured, and you want to separate them so the disease doesn't "spread," or so the other dog can rest and heal comfortably.
Also, if for some reason your Scottie needs to have a vet procedure, he will be in a crate at the animal hospital, and that will add to his anxiety and depression. If he is accustomed to being in a crate, it won't be a huge shock.
Additionally, if your Scottie becomes injured and needs to heal, and you must limit her activity, she won't feel anxious in a crate if she is used to being in a crate to relax.
Having them crate trained doesn't mean they have to stay in the crate day and night. It might mean that they go in their crates every day for regularly scheduled feeding times, and a regularly scheduled daily nap time. It is worth it for you to invest time and effort in ensuring your Scottie's safety and comfort, and thereby helping her to adapt to those situations which might require her spending time in a crate.