But you have pre-existing lands that are compatible w/ this stuff. (Cloudpost, City of Traitors, Ancient Tomb.) Snow stuff is restricted to Snow Lands. It's much more flexible.
I get what you're saying. I don't think that's what they're doing.
1) They did this second set. There would be cards
in the same block that would have different Oracle text than printed text. No way.
2) The only way that <> is relevant is if there are <> costs. You can implement <> costs with pre existing cards without having to re-Oracle all of history. Observe:
Random Colorless Dude 4<><>
Creature - Bloke
(<> can only be paid for with colorless mana)
When ~ enters the battlefield, do a thing
5/5
If you are trying to make a mechanic that locks you specifically into colorless mana, you can do it without needing to change how other cards currently add mana to your pool. It's much cleaner that way. That's why I don't believe they're doing what you're saying.
3) EDIT: plane-specific colorless mana fits right in with the flavor of devoid. These are lands that used to produced colored mana that can't do so anymore because the Eldrazi sucked them dry. They don't produce (1); they produce weird Eldrazi colorless mana.