Even though I actually use #0402 as an office on occasion, I am still limited to conjecture about the seat arangement. From a practical standpoint, it provides more storage space - perhaps something more desirable for the indiviual(s) assigned to #0402.
From a more subjective standpoint, event though the cupola seats are quite comfortable - especially for sleeping, the configuration limits the number of people that can comfortably ride in the cupola. If Jeff Taylor is correct about the individual freedom crews had to configure their cabooses/cabeese, perhaps this set-up made #0402 less likely to be used by someone else that would find its arrangement undesirable.
IMHO, people seem to get territorial over the company-issued property assigned to them, regardless of their profession.