Question about Terminology

[Benji]

This has probably been asked dozens of times, but I'm still new to terminology.

Shouldn't a tornado kick be a 540, and a 540(the one where you land on the kicking leg) be a hyper 540?

When you land on the kicking leg in any other move, they call it a hyper. Why is this one different?

[Source]

Because back in the early days that was the only hypered move. (More or less)
It was called a 540 because when done right you would finish 'backing' the target as oppsed to facing the target like in a tornado or 360.
Now the name has been with us so long that its too much bother trying to rename it. Besides. 540 sounds cool.