Part of the charm of Giallo is that it is dated. Clearly attached to a specific time: the 1970s.
Even though its themes are quintessentially Italian (references to religion, family, the place of women...), Giallo's imagery highly draws on the 1970s' international style: fashion, design, music, everything is an almost perfect encapsulation of this period, which could explain its worldwide appeal and why it's so easy to relate to it more than 30 years down the line.
This is to me the "materialistic" dimension of Giallo: it puts at the forefront of its cinematography all the concrete signs of international modern living of the times.
This typical 1970s contemporaneity is best illustrated by the recurring presence of international travels in the scenarios, through an a posteriori naive fascination for planes and airports. For an obvious reason: international travelling was becoming more accessible and one of the most high-profile symbols of the modern western society: just remember the Boeing 747 mythology.
Countless gialli start or end or are structured by travels on glamorous planes, giving birth to a new figure: the stranger caught abroad in a twisted plot, allowing for multiple points of view on cultural interactions. This is best shown in films like "The girl who knew too much", "The bird with the crystal plumage", "The case of the scorpion tale" or "Short night of the glass dolls", just to name a few.
Perfectly embracing the 1970s' modernity and spreading violence into it like a virus, no surprise Giallo could only then disappear with this decade.
Read Gary Needham's interesting article about the figure of the stranger & post-colonialism here.