Using current GSM (2G,3G,LTE) networks for something like a battery-powered environmental sensor sending just a few bits, once in a while is probably not the most power and cost efficient.
Hence the creation and rise of better suited alternatives.
However, GSM networks worldwide coverage surpass by far those low speed IoT optimized networks today.
It's understandable carriers want to keep being the tech of choice for the explosion of IoT devices anticipated.
IoT pretender Ingenu takes bite at mobile industry
Backed by heavyweight industry figures, Ingenu claims to be building the first nationwide, wireless network in the US dedicated solely to M2M and IoT.