Look a bit farther out than the first world countries you're used to. Reliable energy, and energy to your night stand aren't available everywhere and the countries still sticking to 2G largely fall into that category. Having the flexibility to only need a charging once a month makes these devices actually usable tools.

2G due to its lower information density is also easier to receive and transmit generally allowing significantly lower density of towers and longer reliable range. In largely rural areas there aren't enough customers for companies to invest in towers for the same level of 4G coverage.