Re: How many would be interested to have a device that encrypt directly what u type?
You know what you can develop is something that Encrypt the Private Key when you have to "sweep" it from your Paper wallet to your desktop wallet. 
It will be nice if someone will not be able to keylog your Private key, when you are in the process to sweep it from cold storage to your Paper Wallet.
So you can go offline when you "Copy" the Private Key, then this software encrypts it and then you go online again and it is in memory in a encrypted format and once you logged into your Online wallet and you Paste it.. it will decrypt it and insert it in the field to sweep the wallet.
It is always stressful when you have to sweep a wallet and you do not know if it can be intercepted before you are able to sweep it.
It will be nice if someone will not be able to keylog your Private key, when you are in the process to sweep it from cold storage to your Paper Wallet. So you can go offline when you "Copy" the Private Key, then this software encrypts it and then you go online again and it is in memory in a encrypted format and once you logged into your Online wallet and you Paste it.. it will decrypt it and insert it in the field to sweep the wallet.
It is always stressful when you have to sweep a wallet and you do not know if it can be intercepted before you are able to sweep it.
I guess it'd be safer to automatically/manually generate encrypted private keys which can be decrypted with keys you previously generated to use for safe decryption of all your future private keys that are encrypted.
You get the encrypted private keys and decrypt them automatically/manually on very secure devices or on secure physical environments.
This ^ is recommended on well decentralized system (on full node) so that no one ever knows your decryption keys
I think you missed the suggestion that I made...
What I would like to see ..is some kind of method that will enable you to transfer a "Private Key" in a encrypted state, from say a air-gapped computer or a Paper wallet to a online wallet. So you generate or scan the "Private Key" on another "offline" computer and then you encrypt that key ..before you transfer it to the online wallet.
So when you paste that information in the "Private Key" field, you press a combination of keys and it will automatically decrypt it and you can simply press enter to sweep the wallet to the online wallet. (Example : Electrum)