What the article has not mentioned (may be not big in UK, since this is from wired.co.uk) is that they also own Linkshare, one of the biggest affiliate networks. On its own owning Linkshare is impressive, but combined with Pinterest, you can see the impact of it on online affiliate-driven commerce.
"Englishnization" (which itself sounds like it was made up by a non-native speaker) is a nice thought, but it's going to be downright impossible to correct years of failures on the part of the Japanese educational system. In fact, unofficial reports from employees suggest that it has been a failure - people are still using Japanese pretty much everywhere.
I bet the CEO of Rakuten at a conference in Europe and he seemed like he is very good at what he does and is creating big businesses under the radar. Play.com, a huge brand in the UK that rivals Amazon in media had no association to the Rakuten brand until recently when the logo now includes 'part of the Rakuten group'.