I love the promotions tab for exactly the reason that marketers hate it. If I haven't opened an email in the promotions folder after a week, I've begun unsubscribing from it.
And now a few weeks later my inbox's without the tabs (phone and tablet) are a lot cleaner and more sane.
Newegg and Groupon and other mass marketers _have_ to hate this.
Amusingly you can read the email at promotions.newegg.com
http://promotions.newegg.com/NEemail/Aug-0-2013/GoogleTab14/...