Multivitamins are for people too lazy to eat plenty of vegetables which, in all honesty, is not even that hard.
What you must remember is that RDAs are a minimum requirement, and for optimum health you generally want to exceed them by a lot. That said, if you're eating plenty of good quality fish, meat, eggs, milk, nuts fruit and vegetables then you are unlikely to be lacking significantly in any essential nutrient. If that is the case I simply wouldn't worry about numbers. If not sort it out.
The exception to this is vitamin D. Because we synthesise it from our exposure to the sun, the far greater time we spend inside or covered up in modern life means most people are deficient, especially during the winter months, and especially those with darker skin living in northern countries. Plenty of evidence supplementation can promote health in many ways, and it is common for doctors to prescribe its use. Pregnant or breastfeeding women are encouraged to supplement, for instance.