I was looking at my cell phone the other day (hey, things were a little slow, OK?) and it struck me that it looked like a communicator from Star Trek. Then I found this:
"Star Trek's communicators are now called cell phones - and with web access and photo and video capabilities, are more sophisticated than what the writers of the TV series envisioned back in the 1960's."
So what we have is a situation where some writers dreamed up an imaginary future that contained these devices. Because people watched their show, they came to think of devices that looked like that as futuristic. Therefore, when companies wanted to make a product look cutting edge, they made it look like 40-year-old TV props!