Collaboration. I've noticed over the past weeks that most of the job postings on various sites require on-site working, and it's because of the (mostly justified) need to be able to have a more personal connection to the worker. It has it's great merits, of course, but an employee would usually prefer remote work due to its perks, such as being able to fart where you sit, and not commute to work in what you foresaw from your childhood as a Ferrari.