Some of it for me is pure selfishness. I just care a lot more overall about having an interesting day than being productive. An interesting day includes work and solving problems, but it also includes conversation on both technical and random human topics, connecting with people on a deeper than working level, and just plain screwing around. Luckily this all tends to balance out (at least), because maintaining high spirits and an active imagination gives a boost to productivity that's at least as strong as having a private office and slogging away in it stoically every day for 10 hours.