If you think law has too much room for interpretation when we care about it says, what makes you think anything would improve if we instead cared only about what it meant to say?

The spirit of the law is important in American jurisprudence, but there's a reason that no serious legal academic advocates for abandoning black-letter interpretation: a cornerstone of jurisprudence is predictability. In order to be justly bound by the law, a reasonable person must be able to understand its borders. This gives rise to principles in US law concerning vagueness (vague laws are void ab initio) and due process. We can't always ascertain what the "spirit of the law" is, should be, or was intended to be, but we can always ascertain what the law is. Even in common law and case law, standards must be articulated, and the state must give effect to what is actually said, and not what it wishes had been said. Abandoning this principle in order to "close loopholes" is just inviting bad actors who currently exploit oversights to instead wield unbridled power against ordinary people who could never have even anticipated the danger.

That loopholes are left open deliberately is not a failure of legal interpretation. It's a direct consequence of corruption and regulatory capture. Rewriting American jurisprudence won't solve those problems. Hanging oil magnates and cheaply purchased bureaucrats will.

Following the spirit of the law would be extremely dangerous as one's interpretation of the spirit of the law maybe comply differently from another. There's also the issue of being punished for following what is written in the law only to be unjustly punished for something that's not written anywhere in the law. How are you supposed to trust the law if you cannot rely upon that law to be accurate? The real issue is lawmakers not covering all of every edge case either that be out of ignorance or malice and allowing those loopholes to exist in the first place.

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.

America isn't the land of the free, it's the land of the sociopathic ruling class.