There is a significant difference between "fixing a bug" and "replacing a placeholder with the fully-feature" in a game like DF.
That's true. There are still plenty of bugs and issues that fall into
either category, and a lot of "placeholders" could be replaced with a fleshed-out, less-problematic version with not much cost now or in the future.
I do not personally believe in implementing features that do not work properly, and then leaving them working improperly for years.
As per the add vs fix debate, you have to remember that for every update he's doing 2 bug fix releases, so he's literally doing twice as much bug fixing as updating and you want him to do more? The problem with that is that df is already relatively slow to add new content (or at least release this new content) and adding more bug fixing would only delay that. Bug fixing is important but it can't arrest development in favor of infinitely bogging the project down in fixing systems that might not even exist in a few more updates. Right now the important thing is keeping the game fixed enough to be playable and fun while moving toward the future.
You can't measure effort in number of releases; that's just silly and absurd. You also can't measure
need that way.
You're also making the fairly typical excuses. Yes, it's true that sometimes it's not worth fixing something up past a certain degree because those systems may be replaced. This is not an excuse you can use against any suggestion that more bugfixing or polishing be done. The fact remains that there are plenty of changes and fixes that could be done now, wouldn't really take much time (such as simple raw value problems, to provide the most obvious example), and involve systems that were
just implemented and wouldn't likely be replaced any time soon at all.
In my opinion, what would "infinitely bog the project down" is the continuous implementation of new features on top of new features when the previous "new features" don't actually work right, or have too many problems to reliably produce the correct results.