>After having returned to programming after a hiatus, I have noticed a dearth of hard documentation available (e.g., from Microsoft). What's been behind this move?

I think a combination of things.

MS is more interested in selling products through programs like MSDN, in which case, physical manauls are not practical.

They can charge for the manuals at book stores after you've already paid for the product.

One thousand page manuals are hard to ship and produce.

On top of that, you can't keep them current once they turn into ink on paper.

And finally, I think they're working pretty hard on making manauls obsolete with productivity enhancments directly in the apps they create.