To be fair, the Elf − uniquely − has over a hundred different types.
Even when trying to have three different types of Dwarf − Duergar, Mountain, and Hill − it pretty much immediately merged back into two: Duergar and Dwarf. How many different types of Orc do we need?
The Elf species specifically needs a very flexible and versatile design to represent the many different kinds of Elf. Letting the player choose the spells achieves this diversity, and the concept of an innately magical species makes this spell-centered design appropriate.