That's true. Any decisions affecting the core and the reasoning behind them would be useful at this point.
In fact, it would be really interesting to hear more from pg explaining some of the cryptic comments in the original source and some of the deviations of the current arc from the designs that he outlined in his earlier essays. If the explanation for most of them turns out to be "it was easier" or "it looked better" that's ok, I just wonder some times whether shortcuts and aesthetics explain the difference, or whether there were some deeper, hard-earned insights involved.
At least for nil vs () and a couple of other issues, I've tramped up and down over the territory and reassured myself that there aren't any huge subtleties. I've also tried to ensure (github, unit tests) that any subtleties I find are exposed to anybody following.