There's probably a practicality argument to be made for 90 degree parking to be nose in, because I think it probably results in less blocking of the road is drivers are forced to do the "easier/quicker" front first drive into a spot when arriving avoiding extended time doing "complicated reversing manoeuvres" while other people are trying to get past, and are forced to wait in the parking spot for a big enough gap in traffic (or another driver wanting the spot) before backing out.