what make Shotokan so effective and dangerous?

being shot hurts

You must be new to the martial art. There are many that are effective and dangerous.

FYI Tae Kwon DO is actually derived from Shotokan just more kicking. Does the kicking make TKD more dangerous than Shotokan than? Since kicks are usually to the head, with spin kicks you generate more power, or the infamous dangerous axe kick.

Or even better Muay Thai with their vicious round kicks, does that make it more dangerous?

Or even better ever hear of Hwarangdo or Kuk Sul? Probably not since you already shown your lack of knowledge of martial sciences.

Shotokan (not knocking it) is like middle school. Very basic and simple. Designed to teach the masses in a organized manner.

Other martial sciences are more advanced and are just as if not more dangerous than Shotokan.

When you mature you will eventually see this and maybe learn something more useful than Shotokan.

You may even eventually see the similarities instead of the differences until than you are nothing but a middle school nobody.