Power and Tier Classes

If you desire to become more potent in Minecraft, how about you add base classes (for free) and tiers that grow from the base class you chose?

For example, you select the base class 'warrior', and once you reach exp to level 40, you're able to change to a Tier One; a Gladiator (a player with increased strength but less life) or a Knight (like a tank: more focused on defence than offence). It also takes an amount of Lapis to switch to a Tier One class. If you choose a different base class, the choices for Tier One will change. 

Maybe make a new game mode where this feature is available.

PLEASE consider my idea, I have wanted this dream to come true for a long time.