In brief
Gasho houses are associated with mountain environment and livelihood. The roof should be considered together with the household and the settlement.
Useful to know
The historic settlements of Shirakawa-go and Gokayama are known for large gasho-style houses and steep thatched roofs. UNESCO associates their traditional life with growing mulberries and silkworms in a continuously isolated mountainous area. [1]
This gives more information than the "unusual roof" description. The shape of the home is involved in the economic and social organization of the settlement. Architecture is not just an outer shell to photograph.
When viewing, start from the general profile of the roof, then compare the size of the home with the location of the neighboring houses. The source includes Ogimachi, Ainokura and Suganuma; these are different settlements in the common heritage. [1]
Do not attribute each feature to just one factor such as snow, if the particular source discusses a broader relationship between environment, livelihood, and society. A more accurate explanation allows for several concurrent conditions.
Sources
For further detail and to check the information: