Auto-leveling isn't the answer. First it goes against everything SE is and it'll never happen. Second it just removes any sense of accomplishment about leveling up. So let's focus on how to fix crafting or just go get a bot and stop posting.

One way I could see the crafting system 'fixed' easily is to simply offer a 'quick synth' button. You use this if you just want to NQ something(no chance of HQ) and basically have it 'instantly' completed by performing one standard synth animation. Regular SP, still the same SP requirements, you're basically limited by the number of mats you can afford but instead cut down synth times to a tiny fraction of what they are now. Toss in fail rate to be higher depending on dlvl of the synth you're doing of course. Next to this you can have a 'skilled synth' button that you use the current system to attempt to HQ an item. This would be the only way to HQ anything crafting, and if you were attempting to make something higher above you that you didn't want to auto fail with 'quick synth' this would be your way of doing it.

Another solution would be to go back to a hybrid form of XI's crafting. Instant crafts all based on gaining .1s, .2s or .3s after completing an instant synth. Change up the SP requirements per level, however this would require them to go back and change a TON of drop rates for certain mats to make the difficulty in obtaining materials to synth with, not time to synth or the need to do 500+ synths for rank 49 to 50. It would also make all 'abilities' worthless.

Personally I think crafting should be 'hard' but spending 8 hours just spammin cheap mats isn't 'hard'. I'd more favor it to be expensive gil wise so that not everyone could easily do a 50 craft.