Leves was build as a way for players who don't have much time to play.

See that Yoshi-P would be making a system for Hardcore players which be 8player base dungeons if you not read the interview.

8players: would need to plan out and a good class set to win and times to do.
4players: Don't need much planing it's a go in fight get out type of deal. healer,dps,dps,dps would do in this type of event.

It's seem Yoshi-P have a lot for hardcore and casual play style something tanaka could not do. But at least he still working on ffxiv with Yoshi-P.

So please i know it hard for some ppl to read interview but try and look for them or ask someone if they know before making a topic. Guildleves in few months no one be doing then 2-3years it just be there if you want like ffxi:Garrison