I know where your coming from, but these tests are showing real improvements which once game engines start tapping into, will give us more eye candy. In case of PCIe 4 we have been there already with PCI, AGP x1 x2 x4 x8, PCIe 1.0 2.0 ...
If we were to go back now to AGP x4 with our modern game engines I think you would spot the difference
For now obviously it is a feature which gives something to professionals working with huge data sets, but for gamers it's a non-important logo on a box. In the next 5 years it will be of benefit even in games.
I personally won't upgrade my Threadripper motherboards because of PCIe 4.0 as I have enough lanes not to be bothered with it, but when I decide to do it, it will be nice to be able to visually verify that it works as intended and tests like this are one way of doing it.
But ... PCIe 5 might come before I will do that!