NI is just another tax that goes into the total pot

It's not supposed to be that way though. It has only become that way through many tiny changes so that now it's indistinguishable from "yet another income tax".

The entire point of its existence was to fund the welfare state, including the NHS, and the government we've had most of in the last 50 years absolutely despises welfare. Unless it's for people who already have too much money and businesses "too big to fail" anyway.