I think it is because most of those who are recognised as the great street photographers used B&W. All the best street pictures we see are in B&W and so we are conditioned to think that B&W is best for street photography. It's about tradition as much as aesthetics.
While B&W still dominates street photography there are plenty of great examples of colour street photography.
Well, the question is: do you have the software to work with RAW files? It's not a daft question as not every piece of photo editing software will work with the camera used. Many people had to wait for Adobe to catch with new camera models such as the NEX-5N. If you do have the software then I'd suggest you shoot only in Raw (you could set your camera to record both RAW and JPG but it take more space on your card) as you don't need to worry about B&W or colour, as RAW will record more data allowing you to convert to B&W when you edit the files latter. A good thing to remember is to work on a copy (duplicate) of the original as that will give you a clean copy allowing you to mess around to your hearts context without loosing the data. If you have Lightroom 3, iPhoto or Aperture 3, these will allow you to edit as much as you like with the original file as they all are non destructive, in other words, they keep the imported file and record your edits leaving you with the imported file intact. If you can, go out and give it a test before you go on holiday so that you'll find out how it works before you go away.I am about to go on a trip soon. Its too late to learn to shoot RAW. Not going to chance it.
Shall I take in color and later convert some to B&W or
shall I select my shots in either color or B&W for each situation?
True, but that's a reflection of that photographer's particular style rather than any specific problem with street shooting in colour. Take a look through many of the other galleries on the in-public site and you will see plenty of other examples of colour street photography including work by Joel Meyerowitz.But what you can see in those pictures is that each has a limited range of colours... there is always only one dominating colour!
thanks friend, I was very inspired from these photographs so i went out today...John Goldsmith a photographer who's work I really enjoy, and one particular aspect of his work is his street shots which is in colour (you can see it from his website ) I wanted to bring this up particularly because Eric Kim (another photographer who's work I really enjoy and have attended his exhibitions when he was in town) recently interviewed John Goldsmith regarding his photographic vision and expression, It was quite interesting and informative as he steps away from the typical b&w style of reportage photography and instead captures images from an impressionist point of view.
You can find the Eric Kim's interview from his website here