In that case, it's a slight downgrade security-wise. The standard security model requires the owner of the card to confirm each transaction using a code they receive on their registered phone number. It's 2FA. If you get rid of that, there is no longer a second authentication, and anyone with my card details (which I must protect anyways) would be able to make transactions. Am I correct? Can I at least block the card and freeze its spending capabilities anytime I don't want to use it?
The thing is not ideal when it comes to security, but considering that you can buy an unlimited number of cards, then you can choose the amounts on them in relation to whether you want to use them for online purchases where you have to enter the card data, or you will use the card exclusively to add to Google/Apple wallet on your mobile phone and pay through POS devices that way.
I think that the possibilities of abuse are very small and that it all depends on how you store the card information. It is important that the e-mail you will use to receive the card information after payment is secure, because it seems to me that this is one of the ways that someone could get hold of the card information, unless of course you enter it yourself on a phishing site.