Actually I think that Disney does a good job of telling people they need reservations. Any time I have spoken to them they always ask if I have made my ADRs. Of course if a person books a package from someone
travel agent who is not a Disney expert.. well then they can certainly run into problems.. even if you are staing off site and booking through a travel agent, it is their job to tell you that if you want to eat at a TS that you need to make a ADR.
On the other hand I think that Disney could consider keeping aside several spots for open for walk ups..
Also I can say that I do not have much sympathy for people who spend a lot of $$ on a trip and do not invest in the time to research it a bit. If I was going to Mexico for an all inclusive, I would do some research, if I was going to Europe.. I would research....