That's a fair point, although I'm not sure I would qualify that as "scary".
Given most of the file operations I perform are ones where I'm specifying the filename passed in the variable, I don't see this as a big risk. However, if there was ever a point where the file was specified in by the user and not validated in any way, then doing the three parameter form of read mode would be wise.
For me at least, the right of being lazy is going to win out for this small risk otherwise. I find mistyping to be a bigger worry then intentional mischief.