Any one say: Moore's Law.
Every two years, technology will double.
We may not need it, but if we can research and develop it then we will.
Does any one here need a car that can travel at speeds of 200 mph? No but we buy cars that fast even though we wont drive them faster than 80 or 90 mph on average (yes this is speeding and dont do it).
Do we need a 65" LCD Television? No, but technology allows us to have it and its just as good as a 54" or 42" or even a 37" TV.
Do we need this stuff? Probably not, but because technology can double every 2 years and we can have it, means that we will want it. Whether or not six cores are needed or eight or ten or twelve is not question we should be asking but when, when we will get it?