i like the internal storage on the diverge, whose geometry is almost a dead match for the roubaix (other than the head tube). 1x, of course... but it would make a nice endurance road bike with the right tires.
not having any nostalgia for the old days, i find bags on the bike totally unsatisfying. it would be interesting to know how much of the carefully tuned wind tunnel aerodynamics of a modern road bike is lost when you throw some flappy canvas on there!