You are so wrong. MS does not have a 'low end strategy' unless you count running with plan C (or is it Z?) as 'strategy'.
Right now MS is suffering from it's purchase of Nokia. Nokia pretty much gave up in the last year or so of it's existence, and the crap quality of it's devices and the limited reach of it's higher end offerings really shows that out. The phone production cycle is ~18 months from paper to release, so pretty much everything we have seen MS launch so far is still running largely on Nokia's pipeline, not Microsoft's
Secondly, Nokia had some pretty neat devices in the pipeline set for release last fall in the McLauren devices. These devices had a screen sensor that could detect things like a finger hovering above the glass which could be used to trigger drop-down menus and mouse-like use and gestures. Sadly this technology was not ready for the devices, and the rest of the hardware was not differentiated enough from the current flagships (930/Icon and 1520), so MS killed the devices shortly after the Nokia purchase.
MS is not a stupid company. They are well aware that they need a flagship device or two. They intended to release one as an aspirational device that would get people's attention, which would then push their lower end volume devices. But it was a call between launching a flagship that nobody was going to be thrilled with which would damage their brand, vs holding out until MS's own production lineup was able to be put into place and 'doing things right'.
Personally I think that they made the wrong call. The Icon/930 was not accepted (or generally available) as a replacement for the 92x lineup, and releasing some kind of 935 device that was a little slimmer and had features that we have been asking for of the 930 would have really shown a lot of good-will among WP fans. Even if it was just a minor refresh and didn't have the new finger sensing tech, it would have sold more units and would have been a device that their marketing department and fans could have gotten behind. But instead they are treating it like it never happened, claiming that they are just focusing on devices for 'the next billion' users that the next billion are not particularly interested in.
That being said, MS does have a flagship (and probably 2) in the lineup for release 'with Windows 10' which is expected 'this summer' which will hopefully stem the bleeding and start winning mind-share back. Hopefully it is not too little too late, but with any luck we will see MS make a comeback.