I've seen this attitude from several players. I think a lot of people underestimate the "easy-ness" of gearing up. Basically once you have a 50, you're looking at 1 i90 item every 1.5-2 weeks from myths. I also wouldn't consider it taking "large amounts of time" to gear up in i90. After a week of learning 1-4 it becomes a 1 hour event. 4 runs of AK and 1-4 and you're basically done for the week. I probably play 3 hours a week of XIV and the majority of that is AK.
To OP... You're right. There is extremely little to do once you're on coil. I agree with you being a re-launch there should have been more emphasis on endgame. I couldn't imagine being a legacy player with full 50's and caught up on all class quests. There just isn't anything to do.