I am currently looking at writing a plugin to add support for phpBB3. While reviewing the code of the phpBB2 plugin I realized that giving the user the ability to change the nickname does actually not make not a lot of sense, as it is read-only in phpBB!

So, I have changed the default template to just display the nickname rather than allowing to edit.

(Actually, I might change that back [or at least to some conditional logic that allows entering a nickname if the field is empty]. That way people could get signed up even at a later stage, rather than having to register separately)