I think it's part of MH's plan to turn into a regional (or perhaps more accurately the carrier for 2nd and 3rd tier cities in the Malay archipelago) and more point-to-point carrier without sacrificing the idea/image, especially in its domestic political environment, that they are also a mainline network carrier. There's also the benefit/gamble of connecting 380 million people who are becoming rich enough to afford international travel in the archipelago to westward long-haul/ULH service, without deploying their scarce capital (after all, MH did just have a massive capital injection).

Similar to QF and its refocus on the domestic and Asian market: outsource all of your loss making intercontinental services to a carrier that specialises in a broad network and can do that more efficiently.

EK of course is reliant on having high load factors to pay for its fleet, so that works for them too - as well as being able to bolster their reputation for having a deep network.