Emtpy fields in database

Hello, I noticed that your plugin adds empty fields to database. I mean, wouldn’t it be wiser to check meta field and don’t add if it’s empty? Isn’t it’s just cluttering of database with empty fields?
I mean fields like _yoast_wpseo_redirect, _yoast_wpseo_canonical, _yoast_wpseo_bctitle, _yoast_wpseo_metadesc, _yoast_wpseo_title, _yoast_wpseo_focuskw. Is

http://ww.wp.xz.cn/extend/plugins/wordpress-seo/