Basic motivation..protection from the heat. Wrap over one's face during a sandstorm. Shield one's face from the harsh dry northern cold winds. As a First Aid wrap in an emergency.
And there are other uses I have put my Shamagh to ( different than a shesh but similar usage ).
Of course, now a days it has been used as a fashion statement. Shamagh from the house of Channel, for instance! They all might look alike; just like a suit.
Thanks and regards.