With Korea adding to the list of Android market having Paid apps, the question is, is it good to have your app as a paid app or have ads on it.
There are the markets where paid apps are available
Australia - (English)
Austria - (German)
Canada - (English)
France - (French)
Germany - (German)
Italy - (Italian)
Japan - (Japanese)
Netherlands - (Dutch)
New Zealand - (English)
Spain - (Spanish)
Switzerland - (French,German,Italian, Romansh)
United Kingdom - (English)
United States - (English)
Korea - (Korean)
If you look closely, just 14 out of 46 countries have paid apps, in these countires only 5 countries having English as their primary language, and all the other countries are of different languages. This language barrier is a big factor in selling your apps, especially if your app has a global target.
Why do you have to care about other languages?
As i stated before mobile is not the web. On the web, forums and blogs would copy your content and translate it to their native language or they could use tools like Google Translate or Yahoo BabelFish, mobile apps on the other hand could not be copied and recompiled to other languages and redistributed, thats why it is important that you cater atleast the biggest langauges like English, Chinese, French, Spanish, German, Arabic, Italian, etc.
What does the language have to do with your apps being paid or with ads?
If your app would be in English and you dont have plans to support other language, its pretty bad idea to make it as a paid app (users can forgive you for the ads if its not on their native language). And there are a lot of apps that are paid who are doing this and if your app is just the english language, kindly uncheck the non english speaking countries on the market (Some countries have a huge numbers of non-english speaking/reading so be kind to their paying users)
If English would be the only language in your app then dont go with paid apps.
If you do a paid app 32 other counties would not see your app, which some of them huge market like India (English as big second language) and China.