People will tell you that contemporary poetry can offer nothing new, because there have already been various avant-gardes that have basically done everything possible. The common complaint that some new iteration of the avant-garde is vacuous, because we've already had dada, etc... is less devastating than it appears--for several reasons. The main one is that...

Modernity/modernization is not an event, but a process. You cannot just invent modern poetry once and for all and then forget about it. Nor can you simply return to a non-modern kind of poetry once you have tasted the modern. Even the poetry of the past is changed when we read Hardy through Creeley or Donne through Eliot.