Weight painting. Should this be happening? I was making an animation of the folding of a paper plane. The weight paint seemed like it was deforming the mesh uniformly, despite the fact that there was a gradient in the weight paint. To model this, I created a simpler version of the effect I want to achieve with a plane and a single bone. The weight paint does the same in this case as well:
The plane with its weight paint before transformation.


The same plane with the bone moved along the Z axis.

I thought the bone was supposed to alter the shape of the plane more gradually. Wasn't it supposed to form more of a domelike mesh?
Am I doing something wrong, or did I misunderstood the purpose of the weight paint?

The .blend file.
The difference between weights happens when a vertex is assigned to at least two bones, because Blender normalizes the values: in your example every weight is compared with zero weight on any other bone, resulting in full strenght for every vertex.
If you create a new bone and assign her an equal weight to all the vertices, move only the first bone and you'll see the gradient expected.