Answer 1

They are more visual and interactive.

Answer 2

Some animations etc. look more spectacular than java/c++ output, so people like them more.

Answer 3

Also with the web setting you can interact with the user, make them click at stuff, let stuff happen, while in the 'monochrome' languages you have to enter stuff blindly before you even know what the code is about (which will obviously often lead to an error).