I somewhat agree that "normal" folks won't notice - at least they wouldn't specifically mention anything about stock photos (and these don't look terribly "stocky" compared to others). But, overall the trust or incentive to take the next step that needs to be captured in the first 5-15 seconds will be lower. Even if they can't express it, it just wouldn't feel right in their subconscious.

Also, if possible have the photos set up so the person is facing towards the action you want them to take - the get a meeting room button. Anyways, just a tip, I think it looks very clean overall. And, just went to a meeting room and the onboarding is great. I was in a meeting room within 10 seconds - very nice.