But what if, after checking, you realize that instead of "send $50 to $friend for dinner", you signed "send my life savings to $fraudster"? That's the main attacker model of cryptocurrency wallets.
But more seriously: I've never fully understood why this is such a common issue with cryptocurrencies. My understanding of how Bitcoin works is that you need to actually submit your transaction for inclusion in a block, meaning that you have ample opportunity to verify the transaction's correctness before offering it for submission. Why aren't hardware wallets encouraging that?
If it's on your computer or phone, this means that you trust it enough to not need a hardware wallet in the first place.
If your computer is compromised, you can trust the attacker to take care of the submission for you.
I think the idea is malware on your computer could submit the signed, fraudulent transaction against your will.