With the pointless collecting and the ready-in-three-hours stuff and the sharing with friends, it sounds like they're trying to recreate the appeal of Facebook social networking games stuff... it's actually a really successful business model to base games around an ever escalating series of stuff to get, and to allow (or require) friends to help each other collect them, and to have time-sensitive things that keep bringing the person back.

But it works on Facebook because 1) it's a site that a huge userbase has a reason to keep coming back to in the first place and 2) they sell advertising space and game credits to all and sundry so there's some value in creating a willingly captive audience.

It sounds like the developers behind Pottermore took a look at what worked in the most popular online games and didn't bother to think about why it works, or whether it would work for them.