No need for 128, 256,512,1024 OS and compatible CPU?
Well the biggest example you have,you are using right now. The Internet. Runs mostly on a 32 bit IP address, but now we need a bigger address scheme, hence 64bit was introduce. It was said we would never need more IPs than the 32 bits could address, but yet here we are. If not for NAT the Internet working would have crash years ago.
We can't see the need for 128 or even a 256 right now but the need is there just a little ways down the road. Get your binoculars and look a little further ahead.

It is true however, a 128 or higher OS will not bring faster computing at least not very noticeable anyway. What we need is a complete and utterly new computer system i.e. new bus capable of transfer data near the speed of the 128 bit CPU, storage near that speed as well. In other words the hardware needs to match or approach the speed and performance increase gain by a 128 bit or higher.