How necessary is Gargantuan/Colossal sizing?

[William drake]

In 20XX, when WotC releases 4th Edition, only Red and Gold Dragons get to sizes larger than Huge - all other former Gargantuan and Colossal monsters get their size reduced to Huge.

How would you react to this?

Don't like it, but I don't use all the new books. I think some of them are really bad.
I think you need the different sizes to show variety in the game's scope.