I see the reasoning behind making certain epic destinies favor one class over another but the question is why? Allow the bonuses of an epic destiny not be so specific. Some of the epic destinies work this way but some of them are very specific for certain classes.
For example, Arcane study/draconic/Celestial destiny/ bloodline/vigor of battle passive bonuses
Why CL bonuses that affect those specific classes? Can't see any harm in allowing any class to benefit from CL increases. The list could go on. The benefits should be universal not specific for the most part, we want more customization not less correct? (without unbalancing of course)