And why would a paper wallet created with respect of best practices be not safe ?
Paper wallet IS safe. But spending it is not. (If you are using "sweep private key" and not an offline signing which is very cumbersome).
I know, that's why I asked almost all hardware wallets producers which I know, to include a way to sweep private key from there device in a secure manner.
(when I say secure, I mean offline import of private key to sign, sign and broadcast)
In some years, if my little papper wallet is worst a lot of money, I can insure you I will manually forge the transaction offline, sign it offline, and broadcast on the network.
I tend to consider Trezor and hardware wallets as secured HOT storage (But not as secure as real cold storage). convenient and secure to use to spend everydays bitcoins, but not secure enough to put all the stack in.