Not to mention that everyone complained about Windows 7 when it came out
Not really. It's the famous Microsoft "every other release is a good one" effect.
Win2000 was not received well, because it changed a lot of stuff for the folks using prior versions. But its successor WinXP was a huge win, because it was done right.
WinVista was not received well, because it changed a lot of stuff for the folks using prior versions. But its successor Win7 was another huge win, because it was done right.
Win8 was not received well, because it changed a lot of stuff for the folks using prior versions, and it was really egregiously bad.
Unfortunately, a few years after release, Win10 is still doing battle with the huge success of Win7. Why? Because although the Win10 UI is better than Win8's, it's still an impediment to productivity for most users, who find Win7 a better interface.
Will Win10 eventually succeed? Of course it will. But only because Microsoft will burn Win7 to the ground and sow salt into it, to force everybody over onto Win10. I predict the user base for Win7 will remain for at least a few years after 2020 when the updates stop. I'm guessing by 2020 it'll still have >25% share and it won't drop appreciably for a few years after that.
But eventually the complainers move over to the new edition of Windows. Though it might take 2-5 years