In certain areas landlords do "try" to put low income and market rates rents in the same building. But only because zoning and other laws that force them to. They don't want to and try hard as hell to get around these regulations because they know it cheapens the brand of their high-end building. And just having the low income apartments in the same building makes it harder to sell/rent the nicer units. Call it elitist or whatever, but no one who can afford the penthouse overlooking Central Park in NYC wants their building to have low income units in it.
So right/wrong or whatever, if Apple were to sell a cheap inferior iPhone, some segment of their current market would no longer purchase an iPhone because the brand had been cheapened. Could Apple make up the difference of losing some high-end customers with a high volume of low-end customers? Maybe, maybe not but look at Samsung. They are the volume leader worldwide in smartphones but their profit has taken a huge hit because they've sold far fewer of their Galaxy S5 and Notes than expected and they couldn't make up the difference despite selling boatloads of cheap low-end Android phones. I bet if you talked to the executives at Samsung right now, they'd much rather be in Apple's position right now. And I'm sure Apple has also looked at this and decided they could not maintain their revenues and profit (over the long or short term) by pursuing the strategy you are suggesting. And they have a fiduciary duty to their shareholders to pursue strategies that maintain their position and value.