"No sane system" is your opinion and that's fine. "Only in the US" is a mistatement of fact. That's not true.
It's not just my opinion, but that of most of the world. And even then that of many within the USA. The only exceptions I think are Japan and South Korea (well that's what Wikipedia tells me).
The law is that new machines can be patented and it doesn't matter if the multiplication operation is done by a lever, a gear, on an X86 instruction.
There is a difference. A lever says apply force at this vector and this physical object will produce X result. An X86 instruction, which is just an abstraction of machine code, simply toggles 0 and 1s and is completely generic.
Don't think about it as "changing the law", think about it as harmonising it with the rest of the world. As for the consequences (or traps), you can see that Europe has actually benefited rather than suffered since the inception of software so you don't need to worry that much.