While these tests are imperfect they are the only quantitative information available to gauge one's health. Are they flawless? No, most things in life aren't. Are doctors too eager to diagnose and medicate based on these test results? Oftentimes, yes. But such tests, taken every couple of years (if you're older), can be an early warning detector that something is going haywire ... especially when compared to prior years. For example, if one's triglycerides doubles in two years then it is probably time to re-evaluate one's diet, lifestyle, medications. Same goes for dramatic changes in any of these tests. Even the PSA test, which I forgot to list, can be helpful if it shows a dramatic increase (say, from 1.0 to 10.0).
Now what one does in response to these tests is absolutely up to the individual. If a doctor shrieks "OMG! You need to be put on a statin ASAP!!!" it is best to leave, explore alternatives, and probably get a second opinion. By taking such tests one isn't "giving in" to the medical establishment but rather empowering oneself with (sometimes flawed) information. On balance, I think it's good.