It is my opinion that the main difference between large parrots and toucans it that Toucans cannot use their beak to climb. I think parrots will be able to amuse them self in an environmentally enriched home setting where they will be able to climb and move easy in rooms, including walking..... for a Toucan would be much harder as, to fly, they need a larger space due to their balancing need for the beak, they cannot play as parrots do, they cannot climb... you really need a huge rooms to match their need to keep them as pets properly.
Regarding the wing clipping and rescue birds.. well I have a totally different experience from yours and I have to say that I am really surprised of what you told about the rescue.
I do not mean to be polemic, I am just giving an opinion.. you can keep as pet many many animals, it is about how happy they would be not only how nice and easy they would be as pet.. Toucans may are good pet, they are not aggressive, they are not to noisy or noisy at all and they are beautiful, but what quality of life are they going to have, really?
I have edited this a few times, I hope I have expressed correctly what I mean, without sounding too direct or rude!!