This industry has the unfortunate habit of ignoring psychology and not looking to the deeper level of anything. It's like designers say 'this seems cool and players will like it coz it's fun', which is a derpness that pervades this shitty industry. Great game designers need to look deeper.
An identity is more than a player name: it's the activity taken by that character in the context of the world. When I think back, most of the memories I have of players obviously involved some activity with them or they performed. Bob was a great druid because he evacced at just the right time. Bob wasn't a great druid last night, a decent warrior tonight, and maybe a good quad kiting wizard tomorrow. Multiply this by the number of friends or guildmates a person has in the world, and the number of 'narratives' that must be kept track of to associate with Bob and the others, and what you end up with psychically is a break down of any identity to Bob with the activity, and by extension, his class, that he performed.
What this will lead to is that nobody will really care what class you are or when. It's whatever wanna be at the moment, and this type of mechanic will lead to very weak identity, which will lead to weak attachment to others and the world, which will likely lead to weaker player retention over the long-term in my mind.