One could have said the same things when calculators were invented. Is routine suffering by adding numbers by hand required? Or is it more important to delegate simpler things and focus on complex problems.

Certainly practising mental arithmetic helps in capability of doing mental arithmetic. Doing adding by hand probably also improves mental arithmetic.

The again we are not that far off from time when your AI glasses will read the price label. And then automatically add up total for you. Hopefully you then each time ask what does that total mean in context of your finances...

I learned math long after the advent of the calculator and went on to study math-heavy fields (physics, mechanical engineering, and data science).

I wasn't ever able to really develop deep intuition about/understanding of a calculation until I did it by hand once or twice. I often just plugged in new models and algos just to see if performance was above a threshold, but when I wanted to productionize a new winner, I'd have to run through the algo by hand for a few steps to understand and tune it. And through doing it by hand, the complex became the simple.

The point is not to make the suffering permanent. It is a temporary phase. A lesson. Once you complete it you can go on to do the automated thing without as much concern.