I had a house with mostly Armored Cable and came to appreciate it. Especially after I opened up a floor and found an exposed conductor on some Non-Metallic that had been chewed by a squirrel.
There are still existing functional knob and tube wiring systems that are 100 years old
Guess where I am ;-)
(Not in Chicago/Cook, though.)
I've gradually added GFCI outlets to each circuit. They're not grounded, unfortunately, but they do trip if something were to go wrong. And it allows us to plug in 3-prong plugs without using those horrible 2-to-3 adapters.
We had to change home insurance companies because Amica blacklisted us the instant they heard there was knob-and-tube wiring. A few other companies have the same approach. But it's not like homes are spontaneously combusting everywhere because of it.