[Snake]

A 'cooldown' when swapping classes, and done. I think Dave suggested this back then.

An archer can freely swap between Arbalest and Magic Gunner, but it should be put on cooldown when this Archer goes Soldier, for example.

Also, there's 'History Traits' that can be used as a base for the char's freedom.

And if one is really lacking patience? Sucks to be them, they'll have to waste 1000 Murai/500 Arena Tokens on a fruit. But still, it's like Kameron said, any mechanical solution will prove to be needless work and more of a hindrance. Players 'can' be conscious enough to not be asshats, and omniclassing, sometimes, is accessible by let's say, one vampire who lived since the doomsday.

He would probably know how to do basic grafting, while throwing punches, sword slashes and firing guns. Said vampire won't be able to be the best at everything he learned in life, but he would still be able to do it on the basic levels. As long as 'ominclassing' is reasonable within a character, I'd not mind buying it.

But you know what would solve this once and for all? Skill Points being used for all classes at once, give it 360 Skill Points that can be used 'universally' between the classes.
And Destiny being more oriented on how a class fights for the bonus points, like, 'Destiny: Melee', 'Destiny: Magic', 'Destiny: Spellblade', 'Destiny: Marksman' etc.
And that would reward more points to be spend while removing the classes that doesn't use the said fighting style from the list. (Destiny: Magic people can't spend points in Soldier or Duelist.)

BUT.

Let's not forget the game is still not 100% completed. We need this freedom to find bugs and test shit. If some people are abusing this freedom, they should be just dealt with it instead of wrecking the whole playerbase who's mostly responsible with it.
This is the same problem of 'Grammar' thread, can't be solved without GM reports for warnings.