Why do we need the MMR shot?

The CDC states on its website that, "before vaccines were available, nearly everyone was infected with measles, mumps, and rubella viruses during childhood. The majority of people born before 1957 are likely to have been infected naturally and therefore are presumed to be protected against measles, mumps, and rubella."  In other words, if I'm currently 63 years old, then I'm not at risk for a measles outbreak because I was exposed to the wild virus as a child.  This begs the question, why can't that be the case for today's children?

Additionally, the CDC discussed in the history of measles that, "In the decade before 1963 when a vaccine became available, nearly all children got measles by the time they were 15 years of age. It is estimated 3 to 4 million people in the United States were infected each year. Also each year among reported cases, an estimate 400 to 500 people died, 48,000 were hospitalized, and 1,000 suffered encephalitis (swelling of the brain) from measles."  

Let's break that down. Worst case scenario, if 4 million people were infected and 500 people died, then that would mean 0.0125% of the people that contracted measles would die.  So why did we need man-made immunity with such a low mortality rate?

Furthermore, if one of the reasons to prevent Measles was encephalitis, then why is it listed by the manufacturer as an adverse reaction? These are all the adverse reactions listed for the MMR (Measles, Mumps, and Rubella) product.

Interestingly, almost every single symptom the CDC listed for the wild viruses was matched with an equal or worse adverse reaction from the MMR. ​

The same for Mumps and Rubella, which is also known as "Three Day Measles."

But what about all the outbreaks? What seems to be left out of the news coverage after an outbreak is which strain of measles the outbreak originated from. As listed in the insert, measles-like illness is an adverse reaction. And even the CDC acknowledged that the 1989 measles outbreak occurred "among vaccinated school-aged children."

That outbreak was significant because it spurred the Advisory Committee on Immunization Practices (ACIP) to recommend a second dose of the MMR for all children.  Yet, even after a second dose, the CDC discloses that, "some people who get two doses of MMR vaccine may still get measles, mumps, or rubella if they are exposed to the viruses that cause these diseases."  About 3% of people still get measles even after following the full CDC schedule in addition to an increased risk of all the mumps systems and 52 other adverse reactions listed by the manufacturer. Does this sound like a safe and effective product? And is it needed if natural immunity proved successful just a few decades ago?