It's controversial, just like Reincarnation and Full Character Respec.
The need is in the eye of the beholder. Some people do *want* this ability, but they want it implemented correctly. The old version was obviously flawed and inherently grief-centric. A new system without that flaw would be the best system for a majority that do want this as an option.
Reforming when you're even 25% or 50% of the way through a successful run is one of those things the other 5 players shouldn't have to do because some fellow decides to stay afk and not contribute.
And that's just the piker issue. There are the other disingenuous and disreputable actions that also deserve a good /kick when not following the party leader's request.
I'm sure some people would also love the sweet sweet irony of a zerger running full-speed ahead of the group they joined (that advertised Smell'n The Roses Team-Player Pace!) and eventually dies with 50% of the dungeon cleared by their solo suicide. A well-timed kick would be applauded by the other 5 members and a hearty "Thank-you for making the dungeon easier to explore, but we wanted to kill the monsters as a group."