I always use the 4 color deck option online. Even though I am not color blind nor do I have a sight impediment, it really helps me while I'm flipping through the tables in my smarthphone, it really makes a difference and it greatly prevents the chances of confusing a suit...
Besides that, I wouldn't see its utility in casino tables. Since you virtually can not play more than one table at the time. And even then, if you are really having a difficult time telling between clubs and spades then you should be wearing glasses.