My biggest problem with street photography is that I would love to develop a consistent style, that is recognisable and allows to create a coherent body of work, but I simply can not afford that luxury. Street photography is extremely time consuming, and with full time job and two kids there is simply no time left.
I simply can not afford to be too selective and I just shoot what I see on the street. I can not say "This is an interesting scene, but not what I am after". That is probably one of the reasons many casual street shooters go for B&W. They may claim this is more artsy, it is deeper, creative and blah blah.. but in reality (with some exceptions - dig Pascal Riben for some seriously good b&w street shooting. Then, again, he is not your typical Sunday shooter) it is just easier to have a more or less consistent/coherent B&W body of work, than if you use colour. All backgrounds in B&W all of a sudden start looking the same.
On the other hand street photography is such a broad genre, you can develop some colour sub-genres these days. A wall with people passing by such as the OP image is almost such a sub-genre, just like this:
Walls and People | Photography Forum
One thing is certain - never mix colour street shots with B&W. It does not look good or professional.