Conservative commentator Ben Shapiro once said that although he could argue religiously (he is a Jew), he believes it's a good idea to argue from a secular perspective because God doesn't make stupid laws. Each of God's laws was designed for a good purpose, so even if one does not have a Biblical worldview, it's very difficult to argue against the law itself.
Historically, Israel has had a bit of a mixed past, going through cycles of prosperity and destitution. Each cycle has one thing in common: God. When Israel obeyed God, they enjoyed prosperity, whereas when they rebelled against God, nature itself seemed to be against them.
Sometimes, we see God actively moving to ensure this happens, but what we see more often is that disobeying God's commands often yield their own punishments. As an example, in Romans 1:27, Paul describes how homosexuality was common among unbelievers, and says such people received "in themselves the penalty of their error which was due." God Himself doesn't do anything here (at least not directly), but rather homosexuality naturally leads to some rather unpleasant problems. Even the "safest" practices can damage one, both, or all partners. I don't particularly feel the need to go into the gory details, but this is just one example.
Looking into dietary laws, we see that even those were given for good reasons. Every animal listed as "clean" is relatively safe to cook, whereas "unclean" animals tend to be dangerous, or even lethal, to consume when improperly prepared.
The command against tattoos is not unfounded either. I have three, personally, and every time I went, I had to sign a document acknowledging the risk I was taking by getting them, which included death. Now, if a 21st century trained tattoo artist with the latest technology has to take such precautions, imagine what a 14th century B.C. tattoo artist would have done.
I've listed three examples, and could continue, but what we see is that although obedience to God is not a guarantee of a happy life on this fallen planet, it is certainly more likely to yield such a result, both for the individual and for a nation. Now, I'm not saying we have to obey Old Testament law. The New Testament explicitly tells us that the old covenant has ended. But even the Old Testament laws which are no longer binding had some justification. Clearly, following God's law just makes sense. Rather than being unnecessary restrictions on our life, they are protective measures that increase our chances of a long and happy life. As some people put it, God's laws are not a fence, but a guardrail. Any wolves you find outside the paddock you stray from are your own doing.