Your argument boils down to "Calculating expected utilities is hard, therefore its rarely worth trying."

I think this fails to capture an important point Roko made. If living according to expected utility calculations was merely hard, but didn't carry significant risks beyond the time spent doing the calculations, the statement "trying to run your life based upon expected utility maximization is not a good idea" would not carry much weight. However:

There are many other pitfalls: One is thinking that you know what is of value in your life, and forgetting what the most important things are

This is the real problem, and it seems more about calibration than accuracy.