I'm fine with the single character model, but I do think it discourages trying new things and could lead to people just quitting if they find they're unhappy with changes to their build (nerfs, bugs, etc). This is particularly frustrating because some of these reasons may be only temporary.
What could work is allowing players to archive their character and having a cooldown on swapping it...
E.g: I don't like how magic is playing right now, I want to try a MC/cavalry build. I can archive my mage, making it inaccessible for X amount of days, and create a fighter. If I decide that's not for me, or if a new patch comes out that adds a new magic school or fixes my problems... then I can swap back, archiving the fighter.
This forces the player to be dedicated to whatever they're playing and not having too easy of an escape hatch, but absolves them of the weight of nuking their character permanently - should they change their mind.
What could work is allowing players to archive their character and having a cooldown on swapping it...
E.g: I don't like how magic is playing right now, I want to try a MC/cavalry build. I can archive my mage, making it inaccessible for X amount of days, and create a fighter. If I decide that's not for me, or if a new patch comes out that adds a new magic school or fixes my problems... then I can swap back, archiving the fighter.
This forces the player to be dedicated to whatever they're playing and not having too easy of an escape hatch, but absolves them of the weight of nuking their character permanently - should they change their mind.