I only read OP post and nothing else. Would like to comment about "casual players are people too, remove instant death thing and let them learn their jobs and have fun" part.
The base idea is same as in real life - there are people that are fast learners and people that are slow learners. Then there are people that don't even care to learn and find it easier just to get things get done by others - by whining, leeching or simply waiting for a miracle to happen. I see casual players that play ff xiv just for couple of hours on weekends and know their jobs very well. They only ask for help when they want to do some hard content for 1st time but they also ask for advice or watch/read a guide before. These casual players get end game content done relatively fast. Then there are "the casual players" that basically spend more time in ff xiv than out of it, they usually have 1 or 2 job at level 50, have no idea how to do it proper and talk a lot about "poor mechanics", "broken game" etc.
So - some people are just doing their things quietly, levelling up jobs and learning how to use them well. They progress slower in endgame but they do progress steadily. And then there are some other people that just decide they want to beat THAT DUNGEON/TRIAL. So they spam df or pf never getting past the initial phase of that fight, blaming tanks, dps, healers, Square Enix, lag, cat, mom or whatever else. After 100 wipes they might still have not seen a guide but probably will have made dozens of complaint posts in forums already.