The point here isn't to have more transitions, but rather to put a delay between a yellow going red and a red going green.
People often treat yellow lights as 'Better hurry up!' and the worst of those people will end up in the intersection when the light turns red; if, at the same time, the other light goes green, impatient people will rush the light and accidents (or near misses) can occur. A driver who rushes and then slams on his brakes when he realizes that someone was still in the intersection can be hit by the person behind him who expected him to go, but didn't expect him to stop.
Extremely long lights will make things worse by increasing driver frustration and eliminating the feasibility of left-turns when an intersection doesn't have an advance left turn. In many downtown areas (of the ones which I've been to), there are no (or few) advance left turns; this means that, typically, you will wait at a red light, then wait at a green light, then turn left on the yellow light. If they're on top of things and you've advanced into the intersection, the person behind you could also manage a left turn.
Longer lights means fewer yellows, which means fewer left turns, which backs up traffic even worse.
People often treat yellow lights as 'Better hurry up!' and the worst of those people will end up in the intersection when the light turns red; if, at the same time, the other light goes green, impatient people will rush the light and accidents (or near misses) can occur. A driver who rushes and then slams on his brakes when he realizes that someone was still in the intersection can be hit by the person behind him who expected him to go, but didn't expect him to stop.
Extremely long lights will make things worse by increasing driver frustration and eliminating the feasibility of left-turns when an intersection doesn't have an advance left turn. In many downtown areas (of the ones which I've been to), there are no (or few) advance left turns; this means that, typically, you will wait at a red light, then wait at a green light, then turn left on the yellow light. If they're on top of things and you've advanced into the intersection, the person behind you could also manage a left turn.
Longer lights means fewer yellows, which means fewer left turns, which backs up traffic even worse.