If there's stationary traffic, I'm going to walk through it. Mainly because I believe in the principle that pedestrians should have priority on the road, at least in urban areas. The only reason I'm not going to always walk through moving traffic is that I'd probably get run over. In my opinion (again, in urban areas) traffic should be moving at such a speed that pedestrians can freely wander about.
I ignore the bit in the highway code about not climbing over barriers because I don't believe the barriers should be there in the first place. The fact that they are there indicates that the road has been designed with the motorist's convenience given higher priority than the pedestrian's. The bit in the highway code about not climbing over is perfectly reasonable advice, which I choose to ignore. It's not the highway code that is wrong, it is the barriers.
The way I see it, if everyone is walking, there are not going to be any serious collisions. The problems only start when certain people decide to use mechanical methods of transport in the space originally just used by pedestrians. Therefore, I reckon the onus is on them to take care not to cause the accidents. Why should the pedestrian be incovenienced just so other people can tear about in their dangerous vehicles - cars, bikes, whatever?