Weird flex, but okay...I'll take a crack at answering your questions.
What is the sorcerer's reason for existence?
Well, I can think of a few reasons off the top of my head:
- Because lots of people think they are fun to play.
- Because lots of people wanted a different way to cast spells.
- Because "innate magic" is a popular trope in fantasy literature, JRPGs, and elsewhere.
- Lots of people want more Charisma-based options
Does it have enough traction to continue as a class?
Obviously it does, since it has been included and expanded in the last three and a half editions of the game and will be included in the revised 5E rules later this year.
But as far as "redundant wizards" go, I'd be more concerned about the newer, less popular Artificer.