(I am referring mostly to the common practice period.) Before the advent of well temperament in the 1700s, moving very far from C was not done often because of the mean temperament causing out of tune accidentals. However, disregarding composition exercises such as Bach's Well-Tempered Clavier, why did it take so long for distant keys to become common? Was it because of the relative difficulty of playing in them? Dvorak and the middle romanticists seem to be the first ones to use them regularly, although I don't know every single romantic piece so I might be wrong. But is there a reason other than the relative difficulty that distant keys took so long to become common place after the advent of well temperament?