ablyth

I think almacq's notion of balance is a good one because there always competing purposes in writing a piece of music: something that interests the composer to write; something that interests the audience; originality; understanding; purpose; etc. Trying to meet all the possible criteria is difficult.
I don't think that I suggested composers shouldn't write atonal music. Obviously it still comes back to your notion of audience. If you are a student and your composition teacher is a well-known composer of mostly atonal music, I think it would be reasonable to assume that that person is your primary audience and you will write something to meet their expectations.
In the long term, a composers' first aim should always to be to satisfy themselves even before you start to think about an audience. If what you write doesn't interest you, then it is unlikely to interest anyone else. So if writing atonal music is what does it for you then that is the path you should follow.
I suppose one of the things that makes me wonder is the number of well established composers who suddenly "saw the light" in the 1980's and 1990's and changed musical styles. This was not always that positive a move. Penderecki is one composer whose early pieces are much more interesting than his new style pieces (and thankfully usually shorter and more to the point). It is a bit like the old-style Stalinists who suddenly became new-style democrats about the same time.
More to the point though, I am probably thinking about Schoenberg who, around the time he was developing 12-tone theory, said that in few years schoolboys would be whistling tone rows in the street. Later on he did write an essay in which he recognised that there was very little audience for his music. But i think that there was an early assumption, at least by Schoenberg, that atonality would achieve a measure of public acceptance.