Meh, on the other hand a lot of my Japanese friends have pondered the question of "who decided english would be the world language, and why do we need it" in fact Japanese society has gotten along quite well without it and I'd even argue it's been a blessing - and yes sometimes a curse - but it's offered some protection to their domestic market from being so easily outsourced
or taken-over / dominated by foreign conglomerates. Think of the tens of thousands of customer support jobs that we in the western world find outsourced to india or the philipines each year - I know because I work at a call center and have constantly been moved to new departments as my old jobs keep getting shipped off to india where wages are lower.
Of course there are drawbacks to this but really I think the preservation of Japanese language is extremely safe thanks in no small part to a poorly implimented and questionably useless English education system.
I do agree though that definately, the system is flawed. I just don't happen to think that's necessarily a bad thing.
As for who decided the language, I would say the biggest driver would be "economics", which is in turn a result of historical circumstances.
In order to convince others to target learning a language, you need to have some form of goal. Making money is a good goal.
Being the largest market in the world, it makes sense to target america for trade/business. Japan is #2 now, but it wasn't always that way. Also, since the japanese domestic market tends to favor japanese companies and as such it's difficult to break into those markets.
It tends to be countries in "lower economic positions" that really focus on learning Japanese- China, the Philippines etc... they have a relatively large number of ppl trying to learn japanese. Mainly to work in relatively lowly-placed jobs, or jobs that japanese have no choice but to outsource due to incredibly high demand and low supply- e.g. aged-care nurses etc. This is partially because japanese are very exacting in the levels of customer service that are expected, so any such jobs normally would not favor non-native speakers, simply because they could not guarantee the required minimum level of customer service that is expected.
Not to mention that technological implementation of CJK languages was much harder than latin-based languages- the fundamentals of computers and the internet were based on english, though any language with a simple-to-display small-sized character set would also have worked well. Stuff like arabic and farsi is a bit tougher than english to display, but japanese/chinese/korean is another ballgame all together. The standard english/french/german/swedish/spanish/italian etc is really trivial.
Japan can live in isolation as a country as much as it likes. It will suffer the frustration of not being given any of the political power that it craves as a result, however. It is trying to push for a permanent seat on the UN security council, however whilst it maintains it's isolationist stance I cannot see that eventuating in the near future, no matter how much money it throws at the issue (they are the #2 contributor of funds).