Why these departures from tradition? When it is an official bottling from the distillery itself, usually one of two reasons.
In some cases, a distillery uses different names for expressions having different degrees of "peatiness", in order to minimize the chance for confusion in the marketplace. Springbank distillery's flagship expressions are moderately peated, and Springbank markets unpeated single malt under the "Hazelburn" name and heavily peated single malts under the "Longrow" name. Tobermory distillery's namesake single malt is unpeated, but it sells an almost equal amount of peated expressions under the name Ledaig. The single malts sold by Bruichladdich distillery under its own name are unpeated, and it markets heavily peated single malt under the "Port Charlotte" brand and "super heavily" peated single malts under the "Octomore" brand.
Another reason why a distillery might market whisky under a name other than the distillery name is a business name conflict! Glengyle distillery (owned by the family that owns Springbank) markets its single malt under the name "Kilkerran", because by the time the current Glengyle distillery was established, the name "Glengyle" was already registered for use for a blended malt marketed by another company. Knockdhu distillery markets its single malt under the name "anCnoc" in order to reduce the chance of confusion with Diageo's Knockando distillery.
Usually a distillery's official bottling single malts will be marketed under the name of the distillery, but occasionally that is not the case - and one of these reasons is usually why.