I've said it before, in many games. There are two types of players:

1. Those that get it.
2. Those that don't.

The majority from what I've seen in groups lately.. get it somewhat. Using Red Mages as an example. Most seem to grasp the idea of leading with Jolt to fire up Dualcast. Out of a dozen Redmages I've seen over the last 2 weeks I've only encountered one who didn't. They used Jolt twice or occasionally hardcasted verAero/Thunder without Dualcast.

Here's what SquareEnix ought to do:

Remove 4man dungeons and 8man trials from the MSQ. Or allow a version of it to be played that is entirely solo. Allow the 4 man dungeons and the non-expert trials for the intermediate (average) players, and then your hardest content for the more hardened players.

You can't teach the ones who 'don't get it' how to play 'properly'. They're simply not going to grasp it, or lack the manual dexterity to pull it off. Simplifying the classes won't work. Many of them don't even make the connection between a 123 combo. And you know what? They don't even want to learn, they just want to kick back, read the story and see the ending. Let them have it, but segregate them from the rest so the friction between players is lessened.

ESO does this. The MSQ of that game is entirely solo. You never have to group with a player if you don't want to. You can even get some of the best gear in the game (depending on build) through solo play. Then they have 4 man normal dungeons for those who want to group. Those who want a little more challenge have access to Veteran versions. You basically do the content you can do and are no way pressured to do content beyond your ability. FFXIV could benefit from this example.