Or even easier, implement Homebrew Metamatic that will reduce damage by dice (useable only for spells that have at least 2dX, logicaly) to AoE effect. :P
Make it cost nothing ... and make it useable with any other metamagic.
Voila!
Everyone happy.
1. Chromatic Orb is not a Sorcerer-only spell.
2. Even if it was, that would be an awful hack of a "carpet cover" solution to something that could be fixed on level of the spell and it's attributes to begin with.
An external but related rule that needs to be fixed: Any surface that would inflict a debilitating or debuffing status effect MUST offer a save against its negative effects before applying.
This is something I would really like to see them add to their design-book. It's what saves are for.
