My guess is 95% have never touched one. Another group read the camera was not as good. Only 1% have actually used both.
I like the HTC One M8 a lot and if I gave the phone to pretty much anyone, they would all think it's a quality device.
It's an OK device, and I agree that a lot just don't like it because of the fact that it isn't Nokia or Microsoft. However, some of us also just know what we want from our phones, and the One (M8) doesn't offer it. My cousin's got an Android iteration, and the first thing I thought upon holding it was that it's WAY too slick for my liking (something verified by his penchant for dropping it). While people say aluminum looks/feels better, I personally don't see it as mattering either way. Both the One and my 920 are slicker than I'd like my phone to be, so either one would just get a case thrown over it, which nullifies the aesthetics. People tout the One's build quality, but it's not exactly like the Nokia flagships are poorly built; they withstand all kinds of crap people do to them (mine personally survived a concrete encounter with no damage but a tiny nick in the chassis I found months later).
I'm not a big photo person, but having the camera button on my 920 has led to a LOT more picture taking, and I like that. Giving it up for that One (M8) is just too much of a downgrade for nothing in return. Throw in the lack of Lumia firmware support, and a lot of us don't care to miss out on hardware and software features to switch to an OEM whose interest in the platform doesn't come close to the dedication of what Microsoft/Nokia offers.
I think any level-headed evaluator can admit that the One is a well-built device that is probably the best Android option out there. However, the argument on Windows Phone always seems to be "what's wrong with the One (M8)?" It's never "here's what the One (M8) does better than the Nokia/Microsoft competition." I mean, all I can undoubtedly give the One credit for is the slightly improved SoC clock bumps, and they're not that meaningful. On the flip side, the camera is factually inferior, the hardware is missing features (camera button, wireless charging), and the software isn't as feature-rich (Lumia Camera, which will come, Glance, double-tap to wake, etc.). The last part comes to a preference of aluminum vs. polycarbonate, and I think that most of us either don't care much because both are quality build materials, or we prefer that the polycarbonate offerings include colors to let users feel unique.
So, to circle back as I end this, the response you gave isn't an uncommon one: That many have never held a One (M8), let alone taken it for a spin as a daily device. However, that is often where the rebuttal ends. I never hear the expansion of that argument; if people WERE to hold/try the device, where would the One (M8) shine? What would it offer as an advantage to an Icon/930? Is the battery life significantly better? Is there useful software the HTC offerings hold exclusively? Does the device run cooler? I'd just like to here more actual discussion, rather than just the OP-style commenting of, "why do you hate it? It's pretty nice."