Actually, it's sort of a myth that hardware is fundamentally harder than software. The toolsets simply haven't been as powerful until recently.
Hardware can be thought of as hardcoded software. But it's no longer the case that hardware is hardcoded. Hardware is becoming increasingly sophisticated, especially in their ability to be reprogrammed on the fly.
The line is a little fuzzy, but I'd consider EEPROM to be essentially programmable hardware. x86 has dozens of nonstandard but functional opcodes; how do you know that none of them does something unfortunate?
You don't even need that. You could even just have a completely ordinary, run of the mill, valid opcode do something unexpected when given "magic" data. Like if you mov the value 0xDEADBEEFBAADF00D, the code also jmp's to the top of the stack, as an easter egg.
Regarding hardware reprogrammed on the fly. That sounds like something FPGA is really good at for powerful computation, except, you can't make a sensor detector unless there is already a physical sensor detector attached. It would be cool to make hardware to make hardware :)
Hardware can be thought of as hardcoded software. But it's no longer the case that hardware is hardcoded. Hardware is becoming increasingly sophisticated, especially in their ability to be reprogrammed on the fly.