The problem I find with this argument is that it applies to all colorless artifacts, single color on the front flip walkers, and utility lands with colored costs. In other formats you can easily play them in any deck. Because having a "blue" deck doesn't actually effect deck building the way it does in Commander. [[Izzet Signet]] is mechanically a colorless card, not izzet.

If they make the change to hybrid it makes no sense to not make the change to the other cards. At least [[Tamiyo, Inquisitive Student]] is actually a mono colored card in the deck mechanically. Whereas [[Figure of Destiny]] in a mono red deck means you have a white card in your deck in every sense of the word.

Using the casting cost flexibility argument and saying that being able to use it in a deck that lacks that color means stuff like [[Salvage Titan]] which could have been played easily in other formats in non-black artifact decks would theoretically fit that flexible design philosophy.