Externalized Memory

I've come to depend more and more on externalized memory. By externalized memory I mean things like a todo-file on my desktop, or a post-it on my keyboard, or the calendar in my phone.
If it wasn't for the calendar in my phone, I would never remember things. I'd be at home with no food in the fridge if it wasn't for my calendar.
I think externalized memory is both good and bad, but too much reliance on it is detrimental to the human mind. I knew that I was bad at remembering things, so I started using my calendar. The problem is that when I started using my calendar, I stopped practising my memory for the kind of things i put in the calendar. The good thing is that I don't forget things now, but the bad thing is that stuff that doesn't get written down gets lost in the noise.
For another example, lets look at a GPS navigation system for you car. It helps you find your way with absolutely no problem. I personally don't have one (no money), but I've used them in other people's cars, and they are absolutely wonderful. The problem is that you loose your manual navigation skills when you use one. I know that relying on a map when plotting a trip through multiple countries, or when going to a specific address inside a city can be a bitch, but if you rely completely on your tools, then you can't operate when you are without them.

Now, this could analogously be applied to any computer or mechanization of any task in the world, but you can make distinctions between good loss of memory and bad loss of memory.
If you take a robotic welder in a car factory, chances are you would never ever want a human being in that position, so the fact that the humans no longer know this skill by heart doesn't really matter much, whereas in the GPS example, if you can't find your way around the city you live in without navigational equipment, you are properly fucked.