Front Window Concerns

I notice most of the builds do not have a window in the front of the TD. Is there some reason a front window is not that common? It seems to to me it would be a great option to have for improved circulation and natural light inside the cabin. What are the pro and cons of a front window and are there any structural concerns other than placing the spars/framing in the right place to have the proper size opening. Also, what size restrictions (or anything else for that matter) should I consider? If I'm going to utilize a front window, its about time to purchase it, so I'm looking forward to hearing your thoughts on this.