I mean, they’ve gotta advertise new packs somehow. Before I started looking at the forums, I don’t think I ever heard about new packs other than the in-game screen. Typically I don’t even notice it, though. I just click play and get on started.
Also, most games don’t operate under the business model of dozens and dozens of packs. They sell you one game and that’s it. Most PC or console games with online options (where in which you’re encouraged to purchase upgrades) typically have some crafty way of advertising the online option even in the normal campaign gameplay: See GTA4’s 2 stock markets and other features.