Def Reagan too, firing striking air traffic controllers and then overseeing and writing off blatant union busting and attacks on workers rights at the dawn of neoliberalism was a disaster for us.

But the answer is in your question. FDR didn't give those things away for nothing, it was a conciliation to workers demands. In 1934 a nationwide strike wave shut down a number of cities from coast to coast, and in 1935 we got our new deal. FDR rescued capitalism from the jaws of socialism with social democracy. But the great depression was long and regular people were tired.

During ww2 he asked the workers movement not to strike, and they didn't under the direction of his political ally Stalin. But without the ability to fight, the unions were bureaucratized and businesses organized against labor. By the end of ww2 the american left was gutted and couldn't even fight against passing Taft-Hartley. That last point can't be laid at the feet of FDR as he was already dead.

But FDR doesn't deserve to be lionized, he played his part, legalized a labor movement that had earned its right to exist through our power, not his blessing. And as soon as he died, the right started scraping back those legal protections, so that Taft-Hartley was an easy nail to hammer in our coffin.

"How is good thing bad," you say? The new deal was a tactical retreat on behalf of the ruling class against the ascendant working class. The state exists to manage the interests of the ruling class. Roosevelt wasn't great, he was a representative of his class using the state to maintain capitalist control over the means of production. Once that was assured our rights began disappearing immediately.

Next time there can be no deal. The international, inclusive working class have to take power and fight to keep it, or we will lose it. The old American communists understood this, so had to be destroyed. The sooner we realize the liberal economic order is what brought us here to these horrible conditions, the sooner we can leave behind old illusions about reforms and private property and start to create something real.