Very true. But I do take at face value Google's claims about what each algo is trying to achieve: i.e., that Panda's about thin content/farms and Penguin is about aggressive SEO.
Using my site as an example because it's the only one I can get stats for and so on: my Penguined site was IMO ranking higher than it should have been, and I never understood why. Penguin really just corrected those rankings, which is fine, but also something I don't really understand because of Penguin's stated goal.
--Three years ago, Google was ranking all my content okay. Not too impressed, but finding it somewhat valuable on many queries. I concurred.
--Around the end of 2010, Google suddenly decided that some pages from one of my categories were golden, and ranked them highly on some competitive keyphrases. The pages it had picked were among my most mediocre, IMO, and from a category that my visitors show only mild interest in (it's my third most clicked category by visitors already on site). This is the algo change that puzzles me most, grateful as I was for it. I hadn't gotten any great links to these pages. I believe the algo was responding to on-page factors, but I don't know which ones.
--Penguin time, and suddenly all those high ranking pages stopped ranking so well. Again, I see this as a reasonable correction, as Google figuring out the pages weren't that great, and am only puzzled about why it happened during a "spam" punishing algo.