I'm pretty radical on this topic but for me cognitive load is good, you are making your neurons work and keep synapses in place where they matter (at least for your job). I totally accept writing down doc or howto to make doing some action in future easier and reduce that cognitive load, but using AI agent IMO is like going to bike in the mountain with an electrical bike.
Yes, you keep seeing the wonderful vistas but you are not really training your legs.
So yeah, past a certain age, you'll be happy to reduce your mental load. No question about it. And I feel quite relieved when Claud writes this classic algorith I have understood long ago and don't want to re-activate in my brain. And I feel quite disappointed when Claude misses the point and I have to code review it...