Deerstalker, 18 year old

From the Balmenach distillery. (The previous bottling of this whisky was from a sherry cask. This one is from a bourbon cask.) Mouth-coating in texture. Ripe barley and malty up front, ultimately transitioning to a clinging dryness towards the finish. Notes of vanilla cream, toasted coconut, marshmallow, cut grass, honeydew melon, and lemon/lime. A pleasant, textural whisky. (Bottling at 46% and not chill-filtered enhances this.) My question: why sherry cask or bourbon cask? I think a marriage of both types of cask would add more dimension and complexity.