I wonder if this character limit is related to the metadata issue that we have experienced with CC.  Specifically the addition of metadata through Photoshop and Bridge used to be exactly the same.  Where we input an artist's name for example (under Description) Photoshop would display names based upon previous history.  Bridge will still display this history but Photoshop will not.  The issue did not exist until after CS6.  I believe Adobe could correct this and the character limit.  Strange that the character limit does not afflict Jpgs.  It would be considerate of Adobe to address this important program feature.