oozing liquid? Eww, no! I mean WATER, flowing like a humble brook through a cliff.
Have you ever actually cut a plant open? It's not water in there, it's plant juice. In other words, a sticky mixture of water, cytoplasm, and various organelles - including those that store nutrients - of a type depending on which part of the plant you cut open (you'll get a lot of chloroplast, which, it should be noted, is green). It'd probably taste very faintly sweet, actually. Not as sweet as a bean or other seed-pod, though. On top of being viscous, it has to come through fairly small "gates" that connect all the cells in the plants. And dwarves would probably both try and succeed in brewing it into alcohol. Can you do that with water?
So the DF representation should simulate this in an appropriate manner - by being a slow-flowing, green liquid. And I don't know where this idea that you wouldn't be able to drink it was suggested.
But this is all assuming bean stalks are the way to get up there.
They would much more prefer lands with giant butterflies, flowers, carrots, chickens, harps, and 1-2 giants tops that they get to by climbing a green leafy above ground plant is just oozing with dwarven pride.
Aside from the beanstalk, who even mentioned any of that? Besides, dwarves aren't the only race in the game, and even then cultures are going to become more emergent rather than being fixed to each race.