Some people raise the issue of "brailling" tiles and refuse to play with etched in tiles, such as those that which commonly come with a store bought version of Scrabble. Is this a big deal? Have there been issues in the past with "brailling" in top-rated tournament play? Unless if someone is super good at it, I would imagine it would be easy to see if someone is taking too long to draw their tiles. It seems like too big a fuss for me.
Apparently there is enough of a concern, because according to the latest tournament rules:
Tiles that can be distinguished by feel are not permitted, except as deemed appropriate by the Director for players who are blind.
In addition, to keep players from swapping tiles with adjacent games:
Adjacent games should not use identical tiles.
My finger sensitivity isn't good enough to tell tiles apart, but I'm more than certain that people with better-than-normal finger sensitivity could easilty tell tiles apart.
Etched in tiles can be readily rejected by feel by many players. Picking the right ones is harder than rejecting the Q or Z you're not going to use with your other tiles, but is still a huge advantage.
I can, with inset tiles, often tell when I've got a Q or a Z. Or, I used to be able to; it's been YEARS since I've played. But against friends who couldn't or didn't, I was able to get more tiles I could readily play.
Moreover, it's not a hard skill to practice and to learn, and may not even be consciously done by some players. Even some painted-on-letter tiles have sufficient texture differences to be felt.
So, yes, there is a good basis for the rules against etched titles. It's to keep the game about winning with random draws, rather than feeling for the tile you want.
"Brailling" tiles would probably take some practice, but anybody can feel when they've touched a blank tile, which can be quite valuable.