I think there's some of that in play. If Google can make us afraid of bad links so that we all rush to remove them, for example, that's a whole lot easier than actually creating and testing an algorithm update, especially one of the complexity it would take to do the job.
I also suspect that the 10-day Panda roll-outs and "multi-week" update are, in small part, meant to obfuscate updates. More of us are tracking them, and Google is not a transparent company, IMO.
Finally, I think they're getting into territory that's just more difficult. So many complex updates have collateral damage. I really do think that the multi-week update consisted of rolling out and rolling back changes, and I'm not sure they landed on much of an answer.