custom php variables in template

Ok so, for now, i'm stuck with the 1.5.3 version because the 2.0.1 is breaking every bit of customizing i did, since my website is multilingual.

First of all, why oh why is custom php variables not working anymore inside templates?

Before, with the 1.5.3, templates were separate .tpl files, witch mean that any php code inside will be interpreted on display.
Example:

$lang['NEWS_WRITTEN_BY'].' {author}

would give (depending on language):

News written by (name of author)

in english

Article écrit par (name of author)

in french

Articolo scritto da (name of author)

in italian
etc...

This doesn't work now, it is not interpreted correctly. Even if i put <?php echo $lang['NEWS_WRITTEN_BY'];?> it doesn't work.
Why? why did you do this, saving everything inside conf.php? it is just a big mess for me, separate files were much better...