some people in here cite danger as the problem, others suggest it's about public perception/image and you seem to suggest it's a question of strict obedience of the law
Well, it may be a surprise to some – but all three of those points apply.
A red light does not mean "Give Way" (as someone above alluded), or "warning – busy junction ahead". It is a command. It means STOP. It's not personnal, not meant to specifically inconvenience you, or offer you any choice or discretion.
For those that argue that jumping a light is a "judgement call" – you are correct. Most times, the only person in danger is the rider that takes the (calculated) risk of going through the light.
However,
As a driver, I've had to take avoiding action to miss a RLJer,
As a cyclist, I've almost been wiped out by a bus after a RLJer forced traffic to change line through a turn right light controlled junction, and,
As a pedestrian, I have had to jump out of the way of an RLJer who came through irregardless of pedestrians using the crossing. The old lady walking alongside was not as well placed to evade and just "froze" in the middle of the junction.
Please tell me that such behaviour is not selfish?
In each case the "failure of judgement" was to go through on red without any thought for anyone but themselves.