PB is 10 seconds - so you have time for 4-5 GCD's in that time. That is comparable/better than any other class for that 10 second period.

Our burst is lacking when it's down but I don't think every class should be the same? If you gave everyone the same potency and same cd aoe attacks it may be balanced but what do you lose in response?

Rockbreaker is probably one of the most resource effecient AoE available, if a fight required aoe over a long period a Monk might be superior to the classes. I don't believe any other class has an AoE silence - there may be no encounters that need it now but there may be mechanics that require a monk or that a monk would make much easier later one.