> as long as there is freely available land of sufficient quality
For any reasonable near-term (centuries scale) prospect, there are no serious space or material constraints to outer space. Quality is a different subject, I want to get into that.
> Yet, given the harshness and distances in space, and the fact that land generally obtains value by proximity to other stores of human-produced value
Density of development is fundamentally different in microgravity. Our cities are all 2-dimensional. We can create a space station that hosts a "metro" area of stupendous population where everyone is in fairly quite commuting time of each other.
Of course, we have to return to the "quality" aspect. More work is required up-front to get this sort of thing working. On Earth, we already have many resources that we take for granted for which we would have to devote effort to producing in space. Consider, Oxygen, fresh water, soil, etc.
But couldn't the same thing have been said about virtually every component that went into creating the industrial revolution in the first place? The production of one thing requires support of another industrial product. Enormous production chains are created. Coal products are used in blast furnaces to make steel. Steel is used to make rail tracks to transport coal. Coal is burned to power steam engines to remove water from coal mines. Steal is used to produce those steam engines. Before long, steam engines are used to move coal over the tracks. All of this network goes to create manufactured goods, which make farming more efficient to support more people. In a superficial sense it would kind of sound easier to stay at prior population levels and live with the less efficient farming that didn't have this wild, confusing, and unsustainable web of dependencies.
Why haven't we made progress toward a space-based industrial network of production? You can hardly say we've tried. Through the Shuttle era, launch economics hardly budged. Space programs were turned into science & jobs programs. Manned exploration beyond Earth orbit stopped, and all robotic (indirect) interaction with the rest of material in our solar system ground to a crawl. A major rover like Curiosity takes years to drive as far as the manned lunar rover did in a day, at a tremendous time and resource cost.
Actual exploitation of space resources has so little actually invested in it. The main value we derive from space now is a perch from which to spy on and locate the citizens of Earth. Spending on space is not, at all, focused on something you can "development". Nor has it been. The one time we passed an international law on space resources (the Outer Space Treaty), we came up with incoherent and inaction-able drivel that undeveloped (and presently useless) resources were the property of everyone, and that only governments are really use them.