Not only is it always done, it's not even exclusive to games.
Every major company buys ad and shelf space. Every square inch of a retail store is bought by someone.
Why people are freaking out over Nintendo doing it just shows people have no idea how this industry (any industry) works.
Srsly. Nintendo included ROB the Robot with the NES so they could call it a toy and get shelf space in toy stores, because nobody wanted to stock video games after the industry crashed a few years before.