
Originally Posted by
Jean Christophe Paré
Quite the contrary. You will have a harder time sounding dissonant if you do not establish a tonality, since it wouldn't clash with it. It will be harder to sound dissonant in a truly atonal piece than in a tonal piece, since in a tonal piece you can build expectation and therefore sound extremely dissonant when going against those expectations.
As for your criticism to diminished fifths, I don't think that's reasonable. Yes, it can sound well, but then anything can. On the other hand, diminished fifths have a good chance of sounding dissonant, likely more than a lot of other intervals - minor seconds aside.
Dissonance is a matter of context, and in classical music's theoretical context of harmony and fear of tritones, then a tritone would be well thought if your goal is dissonance.