That's a really good point about non-English content. Most popular community oriented sites out there, service one and only one language. As someone who grew up speaking Turkish, I can tell you that the quality of content in Turkish on the interwebs is quite sad compared to English. Most web sites service a global audience but there doesn't seem to be much i18n l18n going around. This creates a demand for stuff like this. There must be a way to service different languages better without having to clone websites though.
Still, I wouldn't be that nonchalant about stealing work. It's one thing to be inspired by Stack Overflow and build something similar, a 1-1 copy is different.
i18n is a technical issue. What matters most in this case is not that StackOverflow does not have a Mandarin interface, but rather, it does not have a Mandarin community.
Well, which comes first, chicken or the egg? The language support or the community?
Without the community there's no need to support the language. But without the language you cannot support the community.
Part of the problem is that localization can be expensive (especially for non-Western languages) and there is no easy way for community driven sites to gauge potential returns of investing in a new language. But the fact that someone took the trouble of cloning the whole site probably indicates that there's interest out there.
Still, I wouldn't be that nonchalant about stealing work. It's one thing to be inspired by Stack Overflow and build something similar, a 1-1 copy is different.