I like this design philosophy for several reasons:
- Innovation friendly: You can try a bunch of interesting systems and you don't have to rebuild a dozen levels.
- Design testing friendly: You can test these games rather quickly and gather interesting statistics. Gathering 3 - 4 game play data sets per day from a user is a lot better than gathering one data every 2 weeks.
- Minimal plot: I love how they really just 'suggested' a plot with bits of setting randomly strewn about, but didn't really put one there. Good enough for me and a more economical use of development resources.
Here's a dirty little secret. Most game genres are in the form of short games that just happen to be tied together by a simple metagame that relies on plot snippets as a reward mechanism. RPGs? Short tactical battles. Adventure games? Short puzzles. FPS? Short tactical shooting sessions. Remove the story and you still have a delightful gaming experience.