It feels like when you came into this game, OP, you were able to be a sort of 'hardcore' player and move through content at a pace that got you want you needed to progress. That's cool. I used to be that way when I was 25+ years younger. But now, I'm married, and my time is riddled with real life, I realize doing raidlike content and spending hours at a time to farm and learn is something I just can't do.
But ...
Reading the rest of what you wrote seems to me, to stem from your frustration of going from 'hardcore' to 'casual'. Many games have put out new content that makes previous content obsolete (I'm looking at you EverQuest 2). And as annoying as that is, you can still get the older stuff to help you along. There are people out there who I am certain are in the same proverbial boat as you are.
And I get your 'burn out'. Heck, I have 2 characters ... one I do everything I can on (Caleb) and another where I mainly use for RP and wanting to burn through the MSQ (Levi). When I push through the MSQ on Levi, I get seriously exhausted after 2 hours of doing the same thing over and over ... but with Caleb, I mix it up a bit. Having goals to reach really helps. Like yesterday, my goal was to hit lvl 50 on my PLD, finish the Hunting Log, and get the Ironworks Gear. So I mixed it up between those 3 goals and did what I needed to do, all while taking breaks.
And don't worry, crafting and gathering isn't for everyone. And yes, I have 2 full retainers of crafting material, and the 3rd holding my misc stuff. All that, and my character's inventory is full! That's when crafting guides like GamerEscape can help.
Same goes with leveling. When I read you tried to level Tank and Healer at a fast pace, I had a feeling you would stop. That can help with the burnout, but I think at that point you just weren't interested in the game anymore ... especially your feeling on not able to keep up like you used to. Perhaps a bit of vacation from the game might help you get your interest back. And if not, I hope you find something you enjoy!