Quote Originally Posted by SodaDarwin View Post
I know, but this makes them into one-trick ponies. No other race in the PHB is so.
I don't find that to be true. Tiefling and all classes built like them have some low tier spells. Buffed Dragon's breath is entirely competitive with those options.

Lets take Half-Orc for example. They get
  • Darkvision
  • Intimidation
  • Drop to 1 instead of 0 1/encounter
  • Extra weapon on crit

Buffed Dragonborn get:
  • Darkvision
  • Breath Weapon
  • Damage Resistance to one element

While they have less things their things are far more commonly used than Half-Orc.

Tieflings get:
  • Darkvision
  • Fire Resistance
  • non-combat cantrip, hellish rebuke, and darkness

Buffed Dragonborn are entirely in line with the 5e paradigm. What you're arguing for is a 3.X or 4e paradigm.