In any society, some sections would be having 'good times', and wouldn't want the status quo to change. Other sections wouldn't be having a great time, and would be asking for change.

Centrists then might be people who want some changes, although people who don't want any change often also call themselves centrists since (1) different sections would be asking for different directions of change, so staying put might seem the middle ground, and (2) it's more respectable than admitting the current system benefits them and they don't want it to change.

Also centralists are different. Centralisation / decentralisation is the debate over how much power national governments should have versus local governments.