What planet are you living on? Spending wasn't "massively downsized" after the Second World War. It was lower than during the war, but it was way higher than it was pre-war. Same thing with taxes. The top tax bracket in 1940 paid 81.1%. The top tax bracket wouldn't drop below that level again until 1964.
Strangely enough, the bottom tax bracket was a lot higher then also. The reason for that is actually quite simple, the top tax bracket is never the main source of government revenue. If you want higher taxes at least be honest about it and admit you want to tax the middle class so you can pay for all of your pet programs.
I'll freely admit that keeping all existing programs at their current levels of service will require tax increases across the board. Both parties are too cowardly to admit that though.