Traditionally, compiling an application impiled the compiler needed to know specifics of underlying hardware
and/or OS specifics (MS windows, Apple OS, etc). One thing that WASM does is remove the 'have to target
each specific hardware/OS with it's own application' by bundling the 'generic hardware/OS' as part of the
application in a ready to go, one package deal. No 'need to upgrade your OS and/or add outside/beyond the WASM package. It does mean the application is significantly larger than just the application less surrounding environment. Where this is most obvious to the end user is when a application makes use of a graphical user interface. With WASM, instead of 3 different OS looks (Apple, MS word, Unix X11), the WASM application would have same look across all of the 3 aformentioned OS'es. Hopefuly, the application gives the user an option to 'customize the look & feel'.
All previous efforts at providing this functionality have leaked for various reasons, usually because of the addition of "client access" features.
I hope they can resist efforts to make it "easier" in the long run, or we'll have to ride this merry-go-round again.