It's just a proposal, not a requirement.
Even Joshua Lewis, inventor of the new system believes the traditional valuations can make the game more exciting.
"You're really lucky if you pick an X because it's over-valued and unlucky if you pick a V. So if they were to re-do the values of the tiles that would reduce the level of luck.
"That might be desirable in tournaments but it might not be as good in casual play where you want the less skilled players to have a shot periodically at beating the more highly skilled players."
Source: The "British Media"