Why? Because that's the way they wrote it.

Why is the sky blue? Because. ;)

I was hoping for something more informative than this. e.g.
1. This convention was considered more intuitive to the majority of expected
users.
2. Computer programmers live in their own world and have their own
conventions.
3. Other...

And no, there's no way to change this.

Perhaps this should be included in the next version of Excel. Some other
options can be changed with regards to the calculations (by going to "Tools",
"Options", "Calculation"). This would be quite a useful feature.

Thanks
Peter