Wherefore, good sir? I think each role has so much importance that to combine the two might dilute the results. Making sure that such large volumes of data are available, backed up, up to date and consistent seems as important in the future as it is today (only becoming more so as you deal with more and more data). On the other hand, a true understanding of the data without having to worry about where and when it is stored is required to make business decisions, and time taken to do both of those things takes away from the value of whichever one is your primary goal.

I would think it similar to a fighter jet; you want your pilot to be rested and ready to fly the damn thing, not worry about upkeep, that's the mechanic's job. Both highly specialized, both vital, not a crossover position.