Quick note about the storm sorcerer in the Sword Coast Adventurers Guide – bonus spells were removed based on playtest feedback.
— Mike Mearls (@mikemearls) October 25, 2015
Which might sound weird, because people really liked that sorcerer and the bonus spells. However, implementing feedback is never that simple
— Mike Mearls (@mikemearls) October 25, 2015
The original sorcerer is rated very well without bonus spells. Having sorcerous origins with them would make PHB ones look weaker.
— Mike Mearls (@mikemearls) October 25, 2015
The class didn't need the buff, and while people like the idea of the bonus spells, they don't fit with the game's overall structure.
— Mike Mearls (@mikemearls) October 25, 2015
You can expect that kind of revision as UA material enters the environment – we sometimes try stuff in UA to get a sense of future paths.
— Mike Mearls (@mikemearls) October 25, 2015