The only advantage for a low pitched roof is the lower the pitch the less material needed. However, the lower you go the less airspace under your roof and the closer the elements are to the inside of the home.
For example – really low roof rafters with the roof covering just above the ceiling are going to allow for a hotter home in summer and a colder home in winter.
In the 60’s many virtually flat roofed homes with a slight pitch, had a strawboard ceiling with the metal roofing directly above. This type of roofing system allowed for an extremely hot and cold home in summer and winter respectively.
With today’s architecture we are travelling a similar path with low pitched skillion roofs quite the normal. If you are building we suggest to allow for a decent roofspace, to keep the enclosed space as far from the roof covering as possible. 18° roof pitch and above is going to give you best results.
The latest low pitched skillion roofs may look good however you have to live with the consequences for a long time. A gable or hip roof properly insulated with an effective roof ventilation system will give you the best results for many decades of comfort.