Now try selecting between each of the buttons 2cm x 1.5cm for a particular button without having to feel the rest or having to glance at it.
Literally just bumps that are even easier to make than the text on the buttons because they are just part of the plastic mold instead of additional paint jobs. Some people are just hostile to any basic improvement.
We're talking about something most people's minds are not used to interpreting, so I fear that this would just add a layer of mental load for most drivers that would be actually less safe.