I'm surprised at the level of emotion here. People clearly feel very passionate on all sides.
Whilst I prefer to use 'common sense' as my own general guide in life and therefore can see the point of those arguing they use their discretion (2am in the morning no-one else around for e.g.), the fact is that red lights are not a situation at which we are being asked to use our discretion, we are being asked, for the safety of ourselves and all other road users, to stop.
And whatever the ins and outs of what we do each time we see a red light and whatever decision we make, when non-cyclists see someone on a bike go through a red light, whatever the circumstances and whether or not it causes/contributes to an accident, it risks negative PR against cyclists. This comes at a time when the government, the NHS, councils, mental health charities, CTC et al are all trying very very hard to increase the appeal of cycling for the good of all.