Appliances make our lives simpler and more convenient, unless they're located floors away from where we need to access them quickly. Think about your kitchen refrigerator. It's convenient when you're cooking, but if you've ever been in the basement rec room and found yourself in need of a cold beverage, then the kitchen can seem pretty far away. Dorm fridges don't take up much room and can keep cold water, an adult beverage for the big game or even a baby bottle for your kid close by. The same goes for the garage workshop or the lofted attic -- or wherever you spend a lot of time.
Vacuum cleaners are a pain to lug up and down stairs, especially if you have a three- or even four-story house. For that reason, it's smart to get more than one vacuum and keep one upstairs and one downstairs. Your back will thank you.
Clothes washers and dryers are traditionally on the main floor of the house, but having a set upstairs near your bedroom can have its advantages -- especially if you have children and are doing laundry multiple times a week. With a washer and dryer near your bedroom on the upper floor, you can make laundry night a little more convenient.
While on vacation, you might get used to having that cup of gourmet coffee brewing as soon as you get out of bed. If you have even a small, open surface area in your bedroom, there's no reason why you can't set up your own little coffee corner. Single cup coffee makers that brew using individual coffee pods are a good way to go for the bedroom. They don't make much mess and clean up is as easy as tossing out the pod.
These are just a few examples of where multiple appliances can come in handy. Every family is different, and you should customize your home the way it makes the most sense to you. If you decide your rec room needs a microwave or your home office needs its own toaster, go for it. The sky's the limit on what you can do to add convenience and simplicity to your life.