When Vista was released everybody said...well, nevermind, Vista was a POS. When 7 was released, everybody said, XP was much better, because 7 had a lot of bugs to work out, there WERE driver issues from new frameworks, and everything that commonly accompanies the release of a new OS. Same thing with 8, which also really sucked, until they released 8.1, which had the same issues from new frameworks, drivers, bugs, security flaws, etc. Now the same thing has happened with 10, MOST of which have been worked out by now and will continue to be worked out until they decide to screw it all up again.
Hardware support, now at least, not at the beginning, is much more seamless, especially for new technologies, blue tooth devices, thunderbolt, new USB standards, and of course going forward hopefully we're going to see these much touted benefits from things like DX12, Vulkan, etc. People tend to develop selective amnesia and not remember all the problems that each OS version had when it was first released, and for a while afterwards until everything smoothed out. Every version since 3.1, or even earlier, sucked at first until variables and miscellany could be patched, tweaked, revised, adopted, implemented or otherwise "fixed".
I don't know why anybody expected 10 to be any different. There is really nothing graphically that you could do with 7 or XP that cannot be visually reproduced in 10, or even 8.1 for that matter. And in reality, even according to those Techspot benches, wake from sleep is faster on 10, wake from hibernation is faster, cinemark benches faster, futuremark benches faster. 3D particle movement is slightly slower, at least using the hardware they used and all but one of the gaming benchmarks are either the same or faster, except one.
Plus, keep in mind, that review was done immediately following the first releases of Windows 10, before drivers were optimized/revised, or any other code revisions were released. I suspect that with several driver release versions since then and major changes to the OS via the couple of service packs it's gotten, those benchmarks might look a bit different now.