[voidUpdate]

You could vary the heights, but it would have an effect on "clutch power" (how well the bricks stick together), and Lego is very big on making sure that's up to standard. Its often what separates Lego bricks from clones. Also you'd struggle to make a kind of braille pattern on some pieces, like 1x1 bricks.

You could try to make the tops of the bumps textured, but that's where Lego puts their trademark, and I don't think they'd compromise on that, since its another protection against fake bricks that claim they're Lego but are worse. I also don't know how well you could feel textural differences in an area that small

[FarmerPotato]

Injection molding manuals long ago suggested putting some text like the trademark around the point the sprue enters. Camouflage. I had a little Aha moment when I read that and recalled noticing the dimple on old bricks.

With some exceptions (80s plates with sprue on short end) I expect to find the sprue mark on a corner stud.

Anyhow I'm imagining after-market ways to add texture.