This is a reasonable note and I do agree with you that the ideas presented in this essay only capture the increased "glean" of metal (the desirable output of happiness, insights, stories). 

Less ore for me was both a creative liberty I took with the metaphor, but also represented a shift in what levers should be focused on. I would posit that most people now seek more metal with more ore.

"I will be happier if I make more money"

So, less ore is relative to this, not relative to the stable level of inputs a person would be currently at. 

Otherwise, I would argue that not only are "opportunities for increasing inputs are exhausted more quickly", but some would run counterproductive to the fundamental goals of whatever optimization problem. It's hard to determine what will meaningfully contribute to vague and complex ideas like happiness, insightfulness, story-worthiness, etc. Would definitely be interested in expanding on these ideas in a further essay. 

Vacua filling in this article is referring to the planning aspect, and how some plans are better than no plans. The act of following through is another challenge altogether, and maybe certain behaviors can be considered to better increase discipline. 

For example, books like Atomic habits assert "You do not rise to the level of your goals. You fall to the level of your systems." If this is the case, maybe rather than filling vacuums for their own sake, you should instead create habits that fill them. 

All in all, in your example at least that room is quickly able to turn into something of value (a guest room) whereas one that is purely a mess will be much harder to convert into something of use. Additionally, filling vacua randomly with useless things will probably be damaging, so finding some balance is of course important. 

Great point. I believe the essay certainly misses some degree of nuance for the sake of brevity and clear messaging. Taking what I said to the extreme would mean that every hour of every day should be accounted for and planned for, which I disagree with. Life is inherently unplannable and should be spontaneous. 

The note I did want to capture here, is mostly when or if you find yourself with plenty of vacua but seemingly garnering no benefit from their use. While this may be a long thought to cover later, I suspect the interior solution to be something akin to the flexible filling of a vacuum where you can also intentionally choose to cede time to spontaneous events, work, friends, or any number of other options.

So, should the vacuum be 100% filled by you? I don't think so and I don't think I asserted this in the essay, yet maybe my lack of displaying the opposite point implied this.