Look, I'm not going to start the entire helmet debate here on HN, especially since you clearly have not done your research. But to specifically address your points:
1) SWOV has published multiple analyses of this issue. They explicitly noted that the analysis you're referring to was unusual in that it said up to 85 people would be saved per year by wearing helmets. Their other analyses, which use different modes of calculation, arrived at far lower numbers.
2) It's not "a death competition" (but don't worry, America is #1 regardless.) However, every mode of transportation has a cost in lives in many forms. Aside from direct deaths, there are also many indirect deaths from various modes of transportation. If you're going to criticize a possible safety problem in a mode of transportation, keep in mind the broader context. In the Netherlands, where trains are a critical part of the transportation infrastructure, there are more suicides by train than bike deaths (although both are around 200/yr.) You could argue for, perhaps, airport-train-style doors in front of platforms. But that too has an associated cost, and a benefit.
3) You need to consider the consequences of every action, no matter how obscure or strange they may possibly be. Anti-child labor laws sound like a good thing, right? Well, read up on the Child Labor Deterrence Act. Harkin simply introducing the act in Congress was enough to scare manufacturers around the world into action, firing their enormous sweatshops of children. Good, huh? Well, the children were at the sweatshops for a reason. Turns out that without the sweatshops, enormous numbers of children went into prostitution, theft, and rock crushing (which might not sound bad, but it guarantees the destruction of your lungs if you're not killed in a number of other ways.) Every action can have first order, second order, third order consequences...
Finally: 200 deaths a year is an extremely, extremely small number for a system with nearly 20 million users, operating carbon-free, smog-free, at extremely low cost (~20 eur/year.) And it manages to provide fresh air and exercise to all participants! There's basically nothing like it; it's a wonder of the modern world. Risking damaging this system by adding helmets... The payoff is tiny, the risk is enormous.