I created a Jira thing about this, but thought to ask here it has always been like this or if maybe it is a technical reason:
Bumpiness disappears if a texture is rotated towards 90/270 degrees
Create a .5x.5x.5 box, use Default (plywood) texture, set bumpiness to anything (concrete is good), then rotate the texture by holding down on the up button for Rotation.. As texture rotation passes 90 and 270 degrees, the bumpiness disappears.
This occurs with any texture including Blank. Planer or Default.
It makes building something like a brick wall difficult...