Alot of it has to do with training, if a person doesn't see alot of these kicks, they won't use them. Push kicks are used quite often, i use them myself to keep distance, however the type you are describing is not really orthodox. Although, feel free to throw them in a fight, throw what they don't expect to win.

It's really easy to catch a front kick if you know what you're doing. It's also really easy to fall over when kicking high.

There are still quite a few push kicks in thai boxing

They can ko to the head, some can even ko people to the body with them, not sure if that is possible for non giant men tho, its fast, deceptive, economical in motion, and fits in well with combos.

So why is kickboxing something that evolved from karate that has front kicks as a staple kick, so why is it all about round kicks and boxing punches and not about front kicks?