You mean, the advantage of being actually and practically useful? Hmm... I dunno, do we have the support of the French on this?
I doubt it. Although the French language initially started as an ad-hoc construction, today the French have a language purity police. New French words have to be approved, and loan words from other languages are discouraged. Personally, I don't know the details of the agency that does this nor do I know how they enforce it, but it's motivated by a 'preservation of culture' ideal. As a result, hardly anyone outside of French speaking countries is particularly motivated to learn French and it makes it extra difficult to integrate new concepts into the French mindset.
The Japanese do this too, but their language is constructed differently and clarity of expression would actually suffer if verbs and nouns from other languages were integrated ad-hoc. They use a process of segregation, where all nouns and verbs are written in Katakana (their equivalent of capital letters) and verbs are added through the suru construction (like adding -ing on words to convert them from nouns to verbs.) Therefore, the Japanese get nearly all of the flexibility without compromising clarity. This fits into the general Japanese character rather well, which is: Foreigners are really cool and warmly welcomed, as long as someday they are going back home and don't try to actually become Japanese.
French - We are the greatest, most perfect thing ever, and it shall not be soiled by outside influences.
Japanese - We don't insist on being the best, we can learn from others, but we do wish to remain distinct.
English/American/Aussie/etc. - Whatever, who cares how you spell it or pronounce it, so long as it works and you admit that Shakespeare is the greatest playright ever.
Interestingly enough, the Japanese are big Shakespeare fans. Many of Shakespeare's tragedies make the cultural transition to Japan very well.