Reality.

Dreams are as mysterious as life on some elementary level. But on the level we experience them, they might just as well be called "illusions". For all practical purposes I can say that I know to what point dreams are limited, I know the power I hold over them and I get the idea to what it would be like for them to replace waking life. If I disregard everything else, the thought of knowing everything that can be known would screw me up pretty good. The mystery of the universe as something I'll never understand fully is what makes my existence interesting and worth living. Lets just say I couldn't continue to live in "The Matrix" after I'd have been told the truth. Which is pretty much what you're suggesting.

A reality that isn't real, which is how never-ending dreams would probably be experienced, seems like a hellish place to be in, at least experinced by my current state of being. I might not care if I was some buddhist on a serious path to enlightenment, or super-God-lder, but since I'm not, I'd most likely go crazy - the prospect of such a life seems like schizophrenia, but worse.