I don't think this holds true as generally as might seem obvious. Personally I become much more productive and much more creative when I have serious pressure on me. I think art history also speaks to this if you think about all the artists who did their best work (or all their work) under very difficult conditions such as poverty, abuse or simply having been pressed for time.

With all of the tools we've built to optimize our time, you'd think we would be more creative.

The opposite the optimization becomes rigid structure. One thing breaks and the entire pyramid of your life crumbles

Well, we do. But we don’t really use the time we save to do less work we generally use that time to do more.