I am not a sandals or flip flop person, so I always have some type of sneaker on at Disney.
I have the Naturalizer version and wore them at WDW last weekend. I agree that I don't see any physical plusses but, the comfort is amazing. Usually, by the end of a full day, my feet are sweating and have hot spots no matter the thickness or comfort of the socks.
On Sat, I started at Epcot for rope drop and finished at DHS/Last Tour To Endor at 1:30AM Sunday and as I walked to my car, (I try not to use the trams unless it is bad weather - walked over 22,000 steps that day), I realized my feet were ready to keep going. Not sweaty, no hot spots and still walking comfortably.
I plan to look into the less expensive versions so I have an extra pair to trade off. I can definitely say the comfort is worth it. But, as with any shoes, if you decide to buy them, give yourself enough time to break them in and get use to walking in them before the trip.
Karin