Encrypting wallet files does not really solve the fundamental problem. You have to decrypt at some point with keys. The security of this process is what the hd wallet is for
You wouldn't really use that wallet for payments though, just for storage. You can transfer some funds on your every day wallet.
Then I would consider the computer to be part of the system to replace a HD wallet. And it would have a far bigger attack surface than the HD wallet has. Probably also less convenient.
Meant to reply to your other post.
