i know what you're getting at yes depressing, sad poems get old when they're written repeatedly, but (im like this myself) some ppl write poetry when feeling intense emotion often sadness or anger so there is a reason for the repeated poems of darkness and despair.
There's another thing id like to add im suprised you havent suspected this (but you might of) im actually 11 yrs old dont turn all nice on me now as much as criticism can infuriate me its good to do so sometimes so ppl can improve what they have already.