Here is my general position on revisionism: if a change is made to fix something that shouldn't have been there in the first place, or that has been made visible by (a) the higher resolution of Blu-Ray or (b) the lack of generational loss that would have covered up certain special effects secrets (read: wires), I have no problem with that. If something is altered for politically correct purposes or to "protect the children *hand-wringing*", I do have a problem with that. Finally, if a film is altered simply because the director/producer/whatever says "this is the way I always wanted it, but I was hampered by the technology," I call BS.
Ultimately, if the creative minds see fit to alter it, they can, but the with the exception of the first type of revisionism, the original versions should be available in some form. For example, I think Disney should have made the excised scenes in the Pastoral Symphony segment of Fantasia available as a supplement, or through seamless branching. They also could still make them available through BD-Live. Both FFC and Spielberg made the original versions of Apocalypse Now and E.T. respectively available alongside the revised versions; this should be the status quo.