All of these are terrible reasons. The issue is, and will remain, that Microsoft joined the game 3 years too late with Windows Phone 7, then gutted that user base 2 years later, basically meaning that they jumped into the market 5 years late. What's worse, they did it without match the competition in features, let alone apps and games. I can pretty much explain why each point is crap too, if necessary.
1. The 1020 isn't a flagship phone. Its SoC is from early-2012, so it's a fancy camera in a mediocre phone (by 2014 standards). The Galaxy Note 3 and the emergence of other large devices from Sony and LG show that people absolutely will buy the oversized devices that are coming out. I mean, Apple's not rumored to go to 6 inches with he new iPhone for no good reason. Meanwhile, the whole "no glance or SD" is crap because Android doesn't have glance in its stock devices. Apple's never had glance OR SD support. They've both just built a consumer base that requires apps on the platforms, which keeps the customers happy and on those platforms. It's not glance or SD support.
2. That's an overstatement, when talking OEMs. We saw LG and HTC involved with WP7. We've seen ZTE and Huwaei around. We've had Samsung lead WP7 at the start. The OEMs care, but when it's not making business sense because of market share, you can't expect them to deliberately lose money on R&D for new devices, pay for licensing, then get the old "we only like Nokia" response from the Windows Phone supporters. As for the consumers, they don't care because of the app selection. It's not just "people don't care," it's that the OS lacks growth for hardware makers and it lacks the apps for customers because the app developers aren't seeing growth. What it boils down to is still the lack of apps, not "no one cares."
3. Design is not the problem. Look at the iPhone. It took, what, 5 years to stretch slightly? The Galaxy S IV was almost the same thing as its predecessor. Because so few are with Windows Phone, the Lumia design would still be fresh to them, and the color options help to keep that stale rectangle look nice across a group of users. The devices all have some differences between them, as we've seen the high-end with sharp edges and the low-end have the rounded ones, while including thick bodies for wireless charging (920), metal bodies (925), camera bumps (1020), and some other things. I don't think a curved display is going to fix anything.
4. Wireless charging was and is SO much better than those crap examples you gave. Those things don't make the platform. It's the apps, that's the problem. They could get all of those things into the Windows Phone 8 devices, and it wouldn't matter without app developers who use them. Again, wireless charging is there, as is great camera optics. The 3D Touch is allegedly coming, whatever it might be as well, and the 630 had that new Sensor Core or whatever for fitness tracking, and I imagine it will be improved upon and added to t he next device.
5. I've experienced and read about enough Lumia durability to call this crap. The iPhone's glass back once had issues where it'd crack when some tighter-fitting cases were put on it, and those phones have been notoriously fragile forever. I don't even know what to say.
6. Wearables still aren't popularized, and they're confirmed to be in-the-works, basically. Apple's surviving with no watch, as are the non-Samsung OEMS with Android, as they are JUST making such things. Android Wear is just emerging, so the market's not exactly flooded with purchases or convincing products.
7. This is the reason, it's going to continue to be the reason as well. This and platform familiarity/history are the reason. The previous 6 points are garbage things on the furthest-back burners possible to most consumers. My grandma didn't take her Windows tablet back for an iPad because of that other stuff, she took it back because Words with Friends and her slot machine apps weren't present. My sister's friend didn't switch to Android because of a curved display, she was sick of not having apps. My sister doesn't complain that her 822 isn't waterproof, she complains it doesn't have an official Pinterest or FitBit app (though the third-party ones suit her fine).
This is what the WPC forums seem to be covered in though, users who think they know "the answer," which is just a ridiculous click-bait thread with the same, rehashed crap as always. We don't have the apps to draw the masses. That's the problem, shut up about the rest.