When replying to an already posted comment, comment-reply.js (or the 'min' version) is used to move the comment form up to below the comment being replied to.
It also gives the focus to the actual 'comment' textarea. If the person commenting is logged in, this makes sense as it is the only input needed and displayed. If the commenter is not logged in, but has previously commented, the 'author', 'email' and 'url' inputs are displayed, but already filled in, so again focusing on the comment textarea makes sense.
However, on many websites, comments will generally be from casual visitors without logins who have not commented before and so need, at least, to complete the name input, but still the focus goes straight to the comment textarea which seems to be odd, counter-intuitive behaviour.
First question: is there some very good reason why this is the best behaviour which I'm just failing to see?
Second question (assuming the answer to the first question is 'no'): is there a straightforward way (preferably without hacking the core) to modify this, so that the focus goes to the first, non-empty, required field?
(I have tested this on a vanilla WordPress installation, using the 2012 theme, so this behaviour is not the result of a theme or plugin. The comment-reply.js file is located in wp-includes/js and I can see the line which focuses on 'comment'. I have tried googling and searching here on StackExchange, but can find no-one else discussing this behaviour.)