I'd think runes are pretty important of a linguistic tool since many of the jobs one can have in the wizarding world require recognition/decription/knowledge of ancient lore. Also, I think all students that are purebloods should learn runes just on the principle that their Most Ancient Houses have archives that date back lots.

They're also good for highly competitive students that are bored and have time on their hands to prove themselves better than each other.

Alchemy is advanced Potions, approximately.