Casual refers to the level of effort a player will spend to improve their character.
Average refers to skill level.
People contrast power gamers (those who try to eek every last drop of power) from casual gamers who play to enjoy the experience without needing to maximize their character power.
There are casual players with above average skill.
There are power gamers with below average skill.
Skill has little to do with being able to craft or not. Play preferences (causal vs power) have a lot to do with design of a crafting system.
It simply doesnt make sense to design an entire crafting system around the casual gamer.
It would be fine if low level gear (1-12) was designed around the casual gamer, and high level gear (20+) was designed around the power gamer. This would meet the needs of both types of players.