Many people has been complaining about that, due to different facts: Countries with several official languages, people living or just staying not in their own country, companies accessing Internet through corporate gateways in another country, are among the most argued reasons.
So, If you want to choose another different language, just add a parameter with your language suffix (hl=xx).
- German (de) version of Android Market Application and Webstore
- French (fr) version of Android Market Application and Webstore
That can be useful, too, if you want to read comments about any application in other language different than yours.