....Well that's not smart system design, imo.
No, it wasn't... but it was a deliberate move on behalf of the Bitcoin Cash developers. They were trying to become "THE" Bitcoin... so they left everything the same as Bitcoin except for the consensus rules around blocksize... and, thankfully, at the last minute... added in the 2-way replay protection.
Personally, I believe it was more of a political move than anything... but that's just my opinion.
I mean I am not saying this should work this way or that way, I am seeing there's an issue and there were instances in the past when people had same issue and it seems like there needs to be an improvement to the system.
Personally, I don't think the system needs to be improved... but that users need to be better educated and take more responsibility for their actions. A system like Bitcoin that has no "undo" functionality can be very unforgiving.
Everyone was always quick to hype "Be Your Own Bank" as a mantra for the financial freedom being promoted by Bitcoin... However, they conveniently ignored the fact that this should actually have said "Be Your Own Bank, and your own Security Department, and your own Risk and Analysis Department, and your own IT Department" etc.
People are very quick to blame "The System" for their own carelessness and mistakes. Take the time to double (or triple check) what you are doing before you press the "send" or "confirm" button.