A year after WordPress 4.1 introduced a new way to display titles in themes, WordPress 4.4 will deprecate wp_title(). With the change, plugin authors will be able to check for theme support and use a few new filters to manipulate the title. The new filters are as follows:
'pre_get_document_title'short-circuitswp_get_document_title()if it returns anything other than an empty value.'document_title_separator'filters the separator between title parts.'document_title_parts'filters the parts that make up the document title, passed in an associative array.
Theme authors should no longer use wp_title() to generate document titles. If theme authors add add_theme_support( ‘title-tag’ ); to the after_setup_theme callback, the title will be handled natively via an internal WordPress core function. If you use a theme that utilizes wp_title and have wp_debug enabled in WordPress 4.4, you’ll see a deprecation notice.
In general, users who upgrade to WordPress 4.4 won’t notice a difference. However, with nearly a month to go before WordPress 4.4 is released, theme developers are highly encouraged to check and update their themes accordingly.
Now, thats a bit of work to do. Probably overriding titles never been a good practice.
I think Genesis framework use it if add_theme_support( ‘title-tag’ ) is not provided in the theme.