It's only a word unless you've experienced it.
I think I agree, in that language can only express human experience and breaks down when used to represent lofty, abstract concepts, but then again, I think language itself is also necessarily abstract, representative, and communicative, so the true value of words could be that they're tools we use to arrive at mutual understanding.
I've experienced watching a few films that ended with: It's just a dream (It didn't happen) and I was so disappointed...
Have you watched any films (or read any stories) that ended with "it was just a dream" and
not experience disappointment, though? I understand that a lot of them are bad (and I agree that done incorrectly it completely devalues the rest of the work) but I must protest the idea that they are
all bad based on a limited sampling (which any single one of us is stuck with, individually).
Of course, there's a lot left open to individual tastes, etc. I feel that there are many cases where the dream ending is not only appropriate but rewarding, it is simply the context in which it presented. If
Die Hard had ended as all a dream John McClane had had on the flight to see his wife, it would've been very unsatisfying, because seeing him reconcile with his wife after such a conflict is what makes it so good. On the other hand,
Inception's ending with an ambiguous reality is rewarding (in my opinion, anyway) because one of the major themes of the movie is the subjective nature of reality, and a sly, self-referential wink (as I interpreted it) elicited a smirk from me. Who cares if it's real if he's happy?
Context, context, context.