Not so much technical skill, as being able to run one of these "mass" game studios says something about the availability and flexibility of the talent pool. They've been profitable since 2005 so they've been doing something right.

Point being, unless you want to call gamification design, their success was far more based on engineering and business. Like you said it wasn't an original idea, but they could relativly quickly produce a clone of something and monetize. I'm not claiming that this is a particularly great way of doing business, just that it's inaccurate to say that it was design.