That was definitely the case with me, as well.

I'd always stayed away from "overoptimizing". Sure, exactly when Google will revamp their index you never know. But you do know it's going to happen at some point. It'll happen yet again a few years from now.
It's also no secret that going overboard on optimization techniques will end up hurting you. For example - flooding an index page with keywords, but relevant and irrelevant to the site content. Having a list of keywords in the metatags a mile long. Using hidden text on the main page. All those were "optimization" techniques several years ago that the SE's got smart to and cracked down on.
Sames goes for doorways. Same goes for anchor text. As people get wise to how an SE is running their index, the SEs have to stay a step ahead so that they're designating relevance - not the webmasters.
So frankly I just kind of chuckled when everyone flipped out when the hammer fell.
I work with 35 sites - not a one of which got dropped off the index or experienced any real drop in ranking. The opposite was true, in fact. As you mentioned, since so many other spammy sites got dropped - including many ranked higher than my own - lots of my sites got a great boost out of it, getting bumped up a notch as space cleared out ahead of em.

You hit another nail on the head concerning content and substance. You can still have keyword rich text that doesn't go overboard and isn't abusive. Articles, reviews, press releases, and the like are great tools because they have real substance and are also keyword and phrase rich. "Doorway" pages that are standalone, self sufficient, informative and useful sites from the perspective of the surfer and SE are indeed the way to go.

Hell... I still see a few sites I wouldn't mind seeing get dinged. Maybe they'll overhaul the index yet again

Of course, there is certain to be some "collateral damage" from it all. Websites that weren't necessarily spammy or overoptimized and for which the webmasters weren't even optimizing. That weren't being abusive or misleading and were genuinely relevant, good sites but got dropped anyways. But I think that's happened to all of us at some point in time, as much as it sucks.