I'm working on my senior undergrad thesis and did all my interviews over skype or phone, its gonna be really dependent on the question imo. Are you looking to take field notes on how they move or react in real time, or how they showed up to the interview? Or are you just concerned with what they're saying and not as much on their physical presence?
Either that or this professor is just old school, the data I have is still rich and works to answer my question and imo didn't take much away from my data