Very popular rear screen? How would we know that? As far as I know thee is no examples of the same model being offered with the option to choose either rear screen or EVF.
For mid to high end cameraes I assume that vendors will have to offer some kind of EVF, so why keep the rear screen?
For evidence of the popularity of rear screens:
Firstly there is the very fact you refer to, that every one of numerous cameras with EVFs from numerous companies also has a rear screen, despite the disadvantages of some extra cost and bulk. This widespread and unanimous design decision is strong evidence that all these companies judge that a large proportion of customers like the rear screen enough that would accept a hight cost and some more bulk in order to have it. Anf I am one of those strange people who trusts this industry consensus judgement over the opinions of internet forum posters (unless some solid evidence to the contrary is offered). Note that this industry-consensus judgement applies even with the relatively high-end models like the Olympus EM5, Panasonic GH3 and Sony NEX7. Even the new Leica M goes for built-in rear screen, optional EVF.
Secondly, and in answer to your final question "why", try reading the numerous comments in this thread about when and why a rear screen is useful even on a camera with an EVF.
By the way, have you tried using any EVF camera without ever using the rear screen, doing settings entirely with the EVF? The Olympus EM5 allows most settings to be done either way, but so far I greatly prefer doing such things "two-eyed" with the ability to see the buttons and dials that I am operating.