The problem I have with the mechanic Mearls asked about is that it's a different mechanic than the rest of the system, and I'm very much not okay with diverging from the universal mechanic.
The core mechanic doesn't have to be d20 + modifiers versus DC based on difficulty of the task, but it absolutely must be unified across all subsystems.
This is the reason I'm not comfortable having an attack bonus, but no other static bonus to represent training. It's why I didn't like the skill die. Each of these is a fine mechanic by itself, but not within the same game.