That choice can be difficult but there are a few reasons I might choose black and white over color. A black and white photo carries much more emotional impact than a color one. Sometimes the emotional aspect of a photo is the most important thing. Color can distract us from actually feeling the emotion. It is timeless and classic and can help present a vintage vibe. A mystery is developed within the soul of those viewing the photo and if done correctly with the proper hat for instance might make one re-think the value and story of the photo. Using black and white lets you truly focus on the story being told. If you love share, form and pattern you will love black and white. The composition is strengthened as well, in fact try shooting in black and white only for awhile to see the impact it can have on your composition. You will see light differently and really slight more after exploring.
One other thing about out digital world is this, you will see trends as you look around you world since photos are everywhere and those trends are funny in a way in my opinion. Recently I've noticed the trend to convert the photo to a gradient and it seems to me I see this everywhere now. It is as if somebody learned how to do it and now the knowledge has become the norm. But for me, it is strange to see it everywhere.