When retribution or protection paladins find themselves silenced, they are in effect incapacitated. The following melee-oriented "spells" are disabled by silence, if I recall correctly:
Shield of the Righteous
This leaves retribution paladins with the following DPS abilities available: Crusader Strike, Templar's Verdict, Divine Storm. We should keep in mind that when a retribution paladin is silenced, many of the abilities that generate Holy Power in order to use either Templar's Verdict or Divine Storm (which is being changed soon, as should be noted) are rendered unusable. Protection paladins are left with the following two abilities which share a cooldown: Hammer of the Righteous and Crusader Strike.
While it makes sense that these abilities are magical in nature and silence prevents the incantation of magic, it does not make sense that two specs of a melee class are disabled by an effect meant to plague casters whether in PvE or PvP.
I believe a change should occur to move retribution and protection in line with other melee classes in regards to silence. Maybe a talent spec benefit of having certain spells become immune to the effects of silence (i.e., not heals or Exorcism when Art of War is not up) when the main spec chosen is retribution or protection.