I think action scripts are good because they are easy to use.
I don't know about that. It may be easy to get started, but it takes study and practice to become proficient in any programming language. Some are, however, less difficult to learn than others, but even that is subjective.
If you can coder in C++ you really don't need AS...anyone heard of LUA?
I can work in C++, but that doesn't do me much good if my goal is to make a cross-platform game that people can play right in their Web browsers using only a common plug-in. The greatest appeal of ActionScript isn't its level of difficulty; it is about what it enables. It is about being able to make something on either Mac OS X or Windows and deliver it to both of those platforms, to GNU/Linux, and maybe even to some telephones or PDAs or other gadgets.
Having a good programming language is important, but ultimately, it is a means to an end: making software. Capability is much more important than difficulty.