Since their departure from Egypt, Moses had made every attempt to bring the people to an understanding that this physical world was subject to a higher energy known as consciousness. Still, the people held a fundamental belief that physicality was the most important thing. So when Moses wasn't present physically, this created a big problem in their minds. Being committed to the idea of the physical realm as the only reality, they needed someone or something with a physical presence.
We at The Kabbalah Centre are working to change this kind of consciousness, but it's a difficult process. Many of us still worship our physical surroundings… our entertainment, our luxuries.
*Rav Berg on the portion of Ki Tisa.