Why are First/Business Class seats at the front of aircraft where it is the least safe?
There are several reasons:


First In, First Out
They are given precedence to board the airplane before others, and precedence to disembark the airplane before others too.
Quieter Environment
On commercial airplanes, engines are on the wings which are in the aft of first class. Hence first class is quieter, which is a better experience.
Low Turbulence
Turbulence at the front of the plane is lower than the back. Aircraft are extremely flexible and will bounce around more in the back than the because the bump hits the front and causes the back to vibrate.
Seating Arrangement
Important and prominent passengers feel that they should be in the front or on the upper deck (747 or A380), when available. They also feel that they do not need to see other parts of the airplane which are not of their concern.
Marketing Strategy
When economy class people walk through first and/or business class, they will notice the perks and benefits of traveling in these higher classes. They may upgrade their seats on future travels for a higher price.