The tie is also a
socially acceptable BDSM device.
The company is the Master, the top. The employee is the Slave, the bottom.
The tie has links with the collar worn by the bottom, with the tightness of the top button of the shirt around the neck; as well as the leash which allows the Master to grab and pull.
Often, ties also carry the emblem of either the company, or the institution that awarded the tie: be it a previous school, college or university, a society, be it sporting, secret or professional, or an emblem which the wearer chooses. These show who the Master of that particular slave is: perhaps the Alma Mater, the Firm, or Homer Simpson or Grey-type aliens in Christmas hats that play We wish you a merry Christmas when you press the button. It is interesting to note that whilst society- and company based ties are acceptable, as well as geometric shapes that have no meaning, the comic, bright or downright insane ties are frowned upon by society. Perhaps this is because the use of comic ties suggests that the wearer considers himself to be a free man, when his wearing of a tie clearly shows that he is not.
And that is why I wear a tie to work as little as I can get away with, despite it being against the rules.
Bonus credit: why do women get to wear anything they like (within reason!), whereas men have to wear a shirt, tie, long dark trousers and an optional suit? Answers on a /msg, please!