It is posts like yours Ban that allowed the Tories to get away with the restructuring of society. I don't mean that in a nasty way, I mean it as you admit you are no expert and falling for the "we didn't have a choice" rhetoric.
Austerity was purely ideological, it had no basis in economics and it was sold to the electorate in such a simplistic manner it did to be fair border on genius. The notion that running a household is like running a nation is at the core of neo-liberal madness. The Lib Dem Orange Bookists of which Swinson was one were all advocates of social Liberalism with an extreme laissez faire economic approach which was not that different from Cameron, who to be fair was probably to the left of the Orange Bookists economically.
Austerity was a tool used to restructure the state and lower the percentage spend of GDP on public services to American levels. When you consider we have the NHS and the Americans don't then cuts had to come from somewhere to achieve that level of spend. It was ideal to dress it up as austerity in order to balance the books. A feat that has rarely been achieved by our country and one you do not need to achieve as long as there is growth. Austerity stifled growth though and investment fell which meant you had the double whammy of cuts and underinvestment. Was it evil, that depends as the cuts fell the harshest on those with the least and those who relied on the public services the most. If using austerity hurts those with the least then yes it can be considered evil in my opinion because I am sure you remember the phrase "we are all in this together" which of course meant that the rich got tax cuts, so everyone got a cut of some sort.
The problem with cuts is that it sucks consumption out of the market, those with the least have the highest propensity to spend and if you take from those people then it is the local shopkeeper that suffers first and the knock on effect from that spirals upwards and overall demand falls. The Tory answer was supply side measures supported by the Orange bookists and involved policies to increase competitiveness and competition. For example, privatisation, deregulation, lower income tax rates,cutting welfare and reduced power of trade unions. All classical Orange Book tools that appealed directly to Tory free market instincts.
Interventionist supply side policies such as education/training were cut and housing supply dimished as investment was reduced which added to the stifling of growth. IDS tried his idiotic welfare for work policies which were fucking idiotic anyway but classic supply side stuff. The only real acknowledgment to growth was HS2 which is a supply side measure as investment in infrastructure is classical supply side too. The problem with supply side economics is we had a recession at the same time which reduced competitiveness and productivity slumped, wages stagnated and that increased the effects of austerity. The likes of nurses have not had a wage rise for years, in real terms their wages have declined which also hits demand and the vicious circle of austerity magnifies the effects.
I know this is a simplistic answer and it is a long time since I studied Economics and I am getting old, but I hope you get the jist of it. In simple terms my argument is austerity is and was a fucking nonsense but sadly the electorate bought it, because the argument for it was sold to them so well.