It was designed to do so, once that transaction is broadcast-ed and verified things are certain. Its particularly 'bad' for most of the industry use cases where error is prone and rollbacks are essential for recovery plans. Yet bitcoin itself is money/assets, not banks, the network itself doesn't have any oracle layer to govern these transaction and i would say this feature fits correctly for money. Scams and those human traits to get wealthy by exploiting others, much like slaves on the old days. Dealing with these problems should be come from people protecting their private keys, having multiple addresses to safe-guard themselves
Yes, bitcoin transaction on blockchain is irreversible unless it will be send back to you by the person whom you send first and that is one of the blockchain's security so there is no room for mistakes and that is the opportunity that online theft wants, as the fact that blockchain is having no central control and all transaction was done node by node and digitally over the internet.