Well, people have said for years that "Apple doesn't need to do" this or that, and yet they have. So that argument, on its own with no other input, is invalid.
However, and correct me if I'm wrong, I think what you mean is that Apple doesn't do "cheap". And I agree.
The key here is that people are confused about the definition of "cheap", mostly because they're used to thinking about high priced flagship phones.
I'd say that $150 is cheap. OTOH, a $350 smartphone is not cheap at all. In fact, these days it can be a pretty darned nice unit. Certainly plenty enough device for hundreds of millions of potential buyers. Heck, even the $250 devices are more than many people need, and often come with 4"+ screens.
Exactly. Apple has always had an array of devices across multiple price-points in every category, typically ranging from "moderate" to "expensive."
When the iPad was introduced, people were shocked that Apple was able to keep the price so low, but no one considered it "cheap" in the sense of being compromised or shoddy. Even with the advent of genuinely cheap Android tablets (which indeed are compromised and or shoddy) the entry level iPad would have to be considered a moderately priced machine.
So given the market Apple is in, a $300 iPhone is hardly cheap. It would be a solidly mid-level offering, with the genuinely cheap stuff substantially below that (and being the compromised devices that Apple doesn't make).
Honestly, I'm mystified by the number of people that are freaking out at the idea of a relatively less expensive, multicolored iPhone, as if that were a betrayal of Apple's core values. It is in fact business as usual for Apple, the real question being what took them so long.