Because it is fun! But the real answer is: To improve density. Eg, less networking, less power and less cooling and rack space. My understanding is that IX

Because it is fun! But the real answer is: To improve density. Eg, less networking, less power and less cooling and rack space. My understanding is that IX interconnects at 40Gb/s cost not much less than interconnects at 100Gb/s. And if we're going to connect a machine at 100Gb/s anyway, it is better to be running it at 100Gb/s than 50 or 60Gb/s. We need fewer network ports.