And thanks to smartphones, people are used to charging their phone every night, so it doesn't feel like a hindrance like it used to.
Incidentally, 3G capabilities would only be used when the phone's searching for networks or connected to a 3G network (I think), which are becoming very rare nowadays.
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.
It was actually making calls which cut in to the battery, but still it could last 7-10 days with the pattern of usage I had.
That is really what is needed for simple "feature phones"