The system is such that a guest can view (parts of) the board without having to log in and only then decide to answer in a topic or create a topic by clicking the relevant button logging in and
automatically returning to the page after the login in order to submit a post.
Not showing the Reply or create New Topic button is forcing extra clicking for Guests.
Having said that, it's quite easy to "remove" those buttons using the
[3.3][RC] Group Template Variables extension.
But honestly, I think it will irritate your members. I regularly read phpbb.com without logging in and if I do want to reply or create a new topic, I do not want to have to login, and then have to do a couple of clicks to move back to the forum/topic/post, instead of just having to click
New Topic
or
Reply
, logging in and being redirected automatically the the page I was on.
edited: a couple of spelling mistakes + better formulation