Changing someone's class isn't 'mechanical flexibility', but yes, I will eat my words that 'this didn't come out of left field'. Mechanical flexibility, for example, would be multiclassing with no restrictions, basically changing the actual ruleset. Even a semi-generous DM will likely let you re-roll a character in the middle of a campaign and work your story in. Of course, the rub here is that the rest of a campaign isn't often directly designed around interactions, choices, and decisions of your original character but how that character chooses to affect the world.
