Basically, your morality is all wrong. The point of life (for humans, at least) isn't to do what we need - that's only the lowest, most basic level of Maslow's pyramid. It's self-actualization, which essentially means fulfilling autonomously chosen goals. You might see no reason to drive 200km/h, but others might - why limit them? The only potential reason is safety, but hey, people enjoy plenty of extreme(-ly dangerous) sports, so clearly there are reasons to trade off safety as well.
In addition, an appeal to safety doesn't actually make sense in this instance - why would 120km/h be better than 200km/h? I mean, it's slightly safer but still incredibly unsafe! If we prioritized safety over all else, we'd all be driving at most 30km/h! So clearly "safety" isn't a good, objective reason - at best, it's a subjective, arbitrary threshold, but then we ought to recognize that diifferent people will make different tradeoffs regarding safety.