all in one wallet, in my opinion, is not safe, but for walllet hardware, it is certainly safe, which is a problem, you have to buy with a reasonable fee, for better software, use one wallet for one coin.
Yes, I agree with you that we should not put all coins in one wallet. However, I don't think hardware wallet is certainly safe. Of course hackers cannot hack your offline wallet. But there are many causes that can damage your wallet, such as wet, heat, breaking,... so you have to make sure you wallet is put in a safe place