...However, if we ever expect parents, grandparents and less tech savvy people to use Bitcoin, they need to be able to do so using their home PC, with only basic virus and firewall protection. ...
The problem is not (solely) with bitcoin, the problem is with insecure PCs (or bad Android PRNGs or bugs in OpenSSL etc).
Blaming bitcoin is like saying, "if we expect people to use cash, they have to be able to do so with their wallets while at the same time allowing them to leave their wallets full of cash anywhere they visit and expecting them to remain secure overnight with anyone else being able to handle them." Is it the fault of cash that the money would probably be stolen? No, it is the fault of the person who leaves the wallet insecure - in this case both the OS manufacturer and the consumer who continues to buy an insecure OS.
I agree that if we expect others to use bitcoin security must be improved, but even grandparents know you can't leave cash on the counter with your house unlocked while you are out of town for the summer. They need to learn the same thing about their Windows machine. Perhaps if Microsoft, Google, Apple and other manufacturers were liable for security breaches, things would improve, but that is about as likely as the earth starting to reverse its spin in the next minute.
p.s. The headline made me think this was going to be some type of joke - "... Loses $6".