Your photographer will be a big part of your day (and if you have little ones their day too) and if you have someone who is awkward, imposes themselves or worst still makes you or your guests feel uncomfortable that will be part of your memories of the day. With children especially rapport is everything and it can make or break a session.
At my own wedding my cousin fainted spectacularly and stopped breathing right in the middle of the photos. It was a horrific half hour waiting for paramedics and waiting to hear that she was OK (she was totally fine in case you were wondering). Luckily I had a great photographer who of course stopped while all of this was going on and was sympathetic to all the guests. What I really respect about that photographer however was how he got us back on track - we did have photos to take and he needed to get us back in that wedding frame of mind. When I look back on those photos I am eternally grateful that he helped us with this and I got the lovely photos that I wanted. A good event photographer needs to be adaptable, sympathetic, relatable but at the end of the day he or she also needs to get the shots.