The problem with that is that human nature being what it is, those who like to "cut it close" rationalize cutting it closer and closer, because "well, there's going to be a delay before the other light turns green anyway, so I can still make it" or " well, the yellow is going to stay yellow longer, so I can speed up and zip through." Right up until they rely on gaming the system one too many times and hit somebody, usually at a fairly high rate of speed, since they're trying to "beat" an already turned light. Extending the gaps just encourages more people to try their hands at "cutting it close," because most people are lazy and impatient and don't like to wait. I'm not a fan of traffic cameras, but extending the times just encourages more people to run lights, because it gives them a wider margin for error.
In a city near me, when the yellow light times were lengthened back to state engineering standards, the cameras produced so little revenue, an opt-out clause with the cameras' operator (a British firm, BTW) was triggered.
And all studies done that I've read showed that accidents increased at intersections with red light cameras. I suppose a simpleton would say well, they're less dangerous rear-enders, but, well, that's idiotic.