The difference between burn spells that can hit players & creatures vs. those that can't is gigantic.
Red is the only color that *can* punch you in the face with kill spells and it's creatures and lack of card advantage is a balance for that. It's balanced around being able to kill you fast and having limitations on it's kill spells.

This is a (most of the time) upgrade to Magma Spray, but IMO; it's also a bit out of color. It hates on it's ally colors the most (black & green) and the low damage has a harder time killing (or mattering) against White or Blue.

Necessary, but very strange design IMO (even if it's been around since Alpha in the form of disintegrate.)