I just think so much more can be done without levels from a development side of things. We spend years creating content for a 1-50 experience that players blow through and then it's mostly never used again. Factor in the fact that you're making low to level zones for 2+ factions/starting areas and you spend all of that development time on content designed to advance a number. Content for max level players usually suffers, at least the amount provided at launch which leads to people getting bored and quitting not long after.
Levels also cause artificial barriers that help prevent players playing together. Your new buddy just started and you want him to come play with you and your friends but you can't because he's level 1 and you're already 35. Sure there are bandaids like mentoring but that is extra systems that need to be built because of levels.
You can still have progression built into the game. Stuff like having abilities, items and other forms of power boosts found out in the world where you have to find them and it's not just handed to you because your level went up by 1. Add in an AA system similar to EQ and you can still give players the feeling of character progression without them needing to level.
I don't know. I just want a well built world where from day 1 I log in and I'm sent out into a dangerous world to explore and conquer. I don't need 50 levels of grinding to get to the badass part. When I say no levels, I'm also suggesting the world be dangerous enough and your mostly grouping even in "overland zones". You're not running around doing trivial errands, you're out front at the gates where it's like stepping foot into the plane of fear for the first time. Maybe this is why I'm not allowed to be in charge of shit