Honestly other than it being a nice perk, I don't see it affecting reservations for those who really want to go to WDW. As @ParentsOf4 said earlier, Uber and Lyft didn't exist 15 years ago. Now its prevalent everywhere. (Amazingly TDO couldn't get it right for themselves with the MinieVans)
But there were still taxis... and everyone was familiar with the concept. Ride share costs go up when demand is high.. so the price delta that made ride share so popular isn't as attractive as the prices converge.
MDE offered door to door service, it offered luggage transfer, it offered single vendor experience, it offered stress-free availability.
Wait till you try to pickup your uber at the same spot as everyone else at the same time... it's not that pleasant.