Lockouts do provide increased difficulty, learning to take down a ground king in FFXI was very tricky for the smaller shells simply because you had little opportunity to practice. Being able to spam garuda 35+ times in less then 12 hours and get the world first kill is very impressive. I wonder how long it would take to kill Garuda if we had a 24hour lockout with a guaranteed single drop that is loot tradable per kill. If you want to really make the game more casual friendly on the highest lvl's its not helping to allow players to spam an instance 100+ times in a single day, a moderate lockout helps allow the players with less time a much higher proportionate chance at the drops they want.

Garuda / ifrit / AV / CC etc all are easy because of no lockouts and the ability to spam and memorize+optimize every single minute detail of each instance. Their was a need to spam new content when it was new in 1.18~ 1.21 because their was not enough to do. Now their is plenty to keep us all busy we need lockouts and higher drop rates.