Why not? Because the world is not black and white and because we don't speak only one language. And because it is fun.
Since a while I was thinking about a way how to support pages written in my mother language - Slovak. As I'm an IT, 95% of information that I need to read and lookup is written in English. Now my concern was what if anyone writes a really good article in Slovak I'll most likely never find out through the search.
Now I've put things to a test on search.meonl.com. How it works? The search terms are written in one language (English for the moment) and in each column, besides a search engine type, a language can be chosen, and whenever the search term is submitted it is automatically translated, using google translate, to the other language(s). While Google Translate will be never perfect, for basic translation of search keywords works quite fine. In worst case user can rephrase and resubmit.
Only the usage can tell if it will be useful or not as not everyone has a wide screen and not every one can cope with stereo information. Me too likes the clean and plain look of Google search engine, but...
A simple showcases:
For now there is only one localization and that is Slovak, but if I mange to find someone willing to translate the about page and few tooltip keywords there can be also any other (Google Translate supported) language as a primary search language.