They do have some use, depending on the age(s) and weight of the child(ren).
We rented the double stroller from Disney for our twins' first 2 trips, when they were 4 1/2 and the next year when they were 5 1/2. At 4 1/2, they weighed too much for umbrella strollers, and even a double jogger was pushing the envelope. The Disney strollers were pricy even back then, but we just budgeted it into the trip. It made MK after the parade and Epcot in general so much easier to manage.
IMO, Disney strollers have their place. OP, only you can decide what would work best for your family. Good luck!