It depends on the property and the location. If you have type A property and competing rentals offer washer and dryer, you need to provide them as well.
Type B property yes with a slightly higher rent.
Type C, no, unless they rent it from us, typically at $50 extra per month.
That being said, you should definitely offer washer and dryer hookups. It makes a difference in how fast you rent your property.
If you let your tenants bring a washer, dryer or any appliance for that matter, insist on a professional installation. This is a lesson we learned from experience.