Emirates and DXB is all about bringing people and money to the UAE. Emirates is by far the biggest employer in DXB and as such contributes a massive amount of money, indirectly, to the local economy, by way of its staff living here. By moving staff overseas, all that money is lost.
So, yes it is arguably operationally better to have staff based (like Cathay), but it doesn't meet the requirements of the government to bring money to DXB. The operating profit of the company comes a distant second to this overiding philosophy. As a case in point, Ek could easily base much of its cabin crew workforce and save millions of dirhams in salaries and accomodation. But they choose to keep them here regardless of the cost impact on the company's bottom line.
I suggest that the only reason that basings will ever be offered is if reasonable jobs are offered O/S that allow people to live in their home coutries, and we start to lose large numbers of drivers.
dmf