Raison d'etre means "reason for existence" and it refers to a particular thing. The problem is that "why studying algorithms is important" does not describe a thing, so you can ask yourself: the reason for existence OF WHAT?. "raison d'etre of algorithm classes" or "raison d'etre of algorithm research" would be grammatically correct phrasing. Why use fancy words only to get basic sentence structure wrong?

See also: http://grammarist.com/usage/raison-detre/