Add URI Language Identifier to core?

I voted No, because I do not want the framework to dictate how I choose to handle multi-language implementations.

This is absurd sentence .. How you handle languages in a PHP script ? with CSS / JS or with PHP ?
And if you use CI for your PHP code why not to have an easy option to manipulate languages?

And at the end, you are always are free not to use it but to think for another faster and better way to handle languages..

Like query strings? Language subdomains (i.e. en.example.com; this is more common for large companies)? Stored in a cookie or session variable (possibly even on top of a user profile setting)? The HTTP Accept-Language header (in fact, this is the only method that you can argue to be a standard)?

There are many ways and preferences on how to implement this, and there's nothing absurd about the statement that you quoted.