somebody did think of it before.. its called java.. you know the jar file (renamed zip file) with manifest (configuration file). thats all this rp2 junk is, a renamed zip file with configuration file....
You obviously did not read the article. Cloanto itself provided credits and links to previous work in this field, including the W3C.
there are no settings in the xml file, ie: it doesnt say aga, 2mb ram, foo bar baz etc. nothing. so nothing of value-add here yet. so basically serves no purpose...
Again the article explains this too. And the 10 sample games just work, no further config required.
Just think about it: if you add the configuration inside the file, you have to start versioning the file (configurations tend to be improved over time, whereas the game pool is static), it's a lot of work, for the user it's like having MP3 files that need to be updated every few months. It wouldn't have worked.
I would call a file that is simple to maintain and run more than "no purpose"... :-) Or can you do that with any other format?