For the first part, i think its because of the much higher margin that can be achieved by its internet service, as mentioned. So it's some sort of a price bundling strategy. The low-cost phone can be easily sold and expanded into emerging market, so more people will have to use the built-in MIUI system and hence more incomes generated from internet service.The rationale seems to be sound. But still from my perspective, when people start ditching low-price-average quality phones for medium/high-price-good-quality phone, the number of user of MIUI drops anyway.
As for the profitability issue, do you mean the value adjustment of those preferred shares that it issued in the earlier stage of its business leading to the huge losses in 2017???