I mean, the “spirit of the law” itself is extremely vague and allows for even more interpretation than the letter of the law.

You can easily fix the letter of the law by just changing what it says. You can’t fix when the Supreme Court decides that the spirit of the law is contrary to the letter, which they have done repeatedly.

In other words, you’re arguing that we shouldn’t care what the law says, and instead should govern on what we feel the law means.