You're right, MT chips are popping up more regularly and many of the Chinese brands are using them (Xiaomi, VIVO, Meizu, etc)
Not so much in the "Popular" (samsung, LG, HTC) handsets. The Sony M5 was MT powered, but i wasn't really impressed.
SD powered devices are also getting better support in dev/custom rom/kernel space, and given some time and if the MT sources get published, we could see them on even keel eventually
but for now.... eeeeh
There is a reason the Chinese guys use Mediatek. Its a cheaper chipset than the Snapdragon, meaning that their cost to assemble is alot cheaper than say if they went Snapdragon.
Alot of the mediatek chips are pretty solid, and on par with many of last years snapdragon chips, or this years mid range ones.
Many of the Chinese brands such as Xiaomi, Meizu, Lenovo etc are focussing alot on the screen, battery and the overall hardware package. So essentially they want to give you a premium ish looking and feeling device, at a fraction of the cost, and at a fraction of their build costs.
You will also see they doing alot more marketing campaigns, because its something that was lacking to get the brands to be recognised outside of China. Again, by using cheaper but still capable chipsets, they have a bit if freedom to do other thing's to promote their brand