The curved bow (bay) window was intended as an ornamental part of a building rather than a functional one.
A feature of Victorian architecture, the style migrated to countries where the English had a presence, like South Africa. They’re to be found mainly on older houses, although there’s been a resurgence in the residential market. Contractors will bash out the current window and build in a bay window all in 1 day.
The appeal in this case is not form but function because it increases the space in a room without having to undergo extensive building renovations.
The photo below is an example of a curved bow window – or wall – of a modern building. In this case it’s more form than function – decorative, giving the building a distinctive appearance.