I think this was undertoned in the original book. Sorcery is supposed to be the greatest of the supernatural disciplines. Just as the Solars are the greatest of the Exalted (taking after the nature of their creator) and the only Exalted who can learn the third circle of this most powerful of abilities. Having a minimum Occult and Essence rating of five does make Solar Circle sorcery accessible to characters who haven't been around long enough to raise their Essence to 6 but demeans the value of the craft. On a related note I think thaumaturgy is a bit too dull. It's supposed to be magic so tame that even mortals can practice it because it's based on manipulating Essence patterns to do things they can do anyway rather than creating new ones but could do with more spice.
Sorcery however is supposed to be greater than the most impressive feats of shapeshifting or Sidereal martial arts. So why does the highest level or sorcery have a pathetic trait minimum level of five for it's greatest expression. Sidereal styles have Essence 8 Charms and Lunar shapeshifting is a direct partner of their ordinary powers. So I decided to create the following rules to give Solar Circle sorcery (in fact all sorcery) the rarity and distinction it deserves.
Terrestrial Circle Sorcery Minimum Occult and Essence: 5
Celestial Circle Sorcery Minimum Occult and Essence: 7
Solar Circle Sorcery Minimum Occult and Essence: 9.
That should demonstrate just how demanding and potent sorcery is. And be a mark of how difficult to learn the greatest of the supernatural disciplines is as well as a comparison of it's power in relation to other Charms.
