Cell sites are more expensive than adding additional carriers and take longer. Also no carrier is going to build a nationwide 2600mhz network, but to use it for capacity is very smart. Have a sub 1Ghz band to build coverage, and a high band for capacity. Our data usage is still growing at an exponential rate, and who knows if it is going to subside. Now phones can play HD video, and we have apps like youtube, Netflix, etc. That spectrum is going to be useful in the future in cities, rural areas not so much.