Kureru is an expression of gratitude—your gratitude—so it doesn't make sense for any verb that doesn't bring benefit in your direction. Not only do Japanese speakers say "thank you" explicitly more often than in English, using the word arigatou (ありがとう), but the grammatical thankfulness of kureru imbues many sentences, especially but not only those related to social relationships. If ageru involved flipping the direction of a verb's "benefit arrow", yagaru (やがる; becomes yagatta in the past tense) keeps the arrow in the same direction—seeing the action as the receiver—but inverts the sentiment that is involved.