You're forced to give up several ways of communication which are valuable. You can't walk into a colleagues office for a quick whiteboard discussion. You have to schedule time when both of you are available. Not only that if the discussion brings up things that other people are working on you have to again wait and schedule time with them too. You also can't pickup on non-verbal cues, which can tell you if they're nervous/apprehensive/unhappy about something in the project, etc. You give up laughing at silly things over lunch, or sharing a quick joke as you pass someone in the hallway, or giving someone a hug on their birthday. All the little things that do lift your spirit when you're frustrated or feeling a bit low.