It's popularly understood that the Apollo program only selected lunar-orbital rendezvous as a mission profile after first thoroughly rejecting the direct ascent profile. It seems as though the decision to go with LOR was highly controversial at the time, because it was seen as very risky relative to the other options (earth-orbital rendezvous and direct).
My question is -- why? In retrospect, of course, lunar-orbital rendezvous not only turned out to be the "right" solution from a design perspective, but it was largely a non-issue (notwithstanding the challenges of Gemini 4). To me, rendezvous seems to be primarily a problem of orbital mechanics, which is purely basic Newtonian physics. Of course, as Gemini 4 demonstrated, it isn't a trivial problem... but why was it not seen as a solvable engineering problem? Isn't it much less complex than the risky and dramatic engineering needed to build bigger and more reliable rockets?