As opposed to a 30s CD CB which also does damage plus Shield Bash Plus heroic throw plus Spell reflect Plus Charge/etc?
As it is, part of the problem you've highlighted is an issue also faced by Ret...the use of an AoE tool - in this case, Avenger Shield - in all rotations. There was little wrong with AS having a specialised use and be on an appropriately longer CD but Blizzrad seems reluctant to give Paladins the full toolkit the spec needs. AS is a good ability, but IMO it shouldn't be part of a standard rotation....the silence makes it ideal for caster pulls, and for specialised situational use whilst in combat. Its not something that should be tied into a proc mechanism....HoW would be a better fit there if that wasn't the classes execute move.
Truth is, the class is hurt and held back more by the lack of offensive moves which forces Blizzard to overload the few that are available with secondary effects and limits the chocie of such abilities when they are needed to tie into various procs.
EJL