" don't think that complaining will get you your old interface backspamming Apple with "I HATE YOSEMITE" messages isn't going to help anybody. "
+1 to not spamming, but "I HATE YOSEMITE" is a reasonable comment.
I encourage people who dislike (or hate) the appearance of Yosemite to make clear their emotions in feedback to Apple. If that feedback can include a detailed explanation of why there's a negative reaction to the design, even better if a problem (or perception of a problem) is reproducible, that's ideal.
As I said earlier, it's always been Apple's way or the highway. That's how it's always been done. The people who hate Yosemite that much are gonna have better luck moving away from OSX than getting Apple to rapidly change things again.
A lot of it is the whole change thing. People are massively resistant to change. I've learned to embrace it as I have any design decisions Apple have made as that's what I signed up for when I bought a Mac. That's Apple's way. I HATED when they changed the 3D dock from the Leopard style but I learned to deal as there was no changing it. Same with the visual changes of Yosemite. They may tweak things but the big UI change is here to stay I'm afraid until it becomes dated and Apple decides to redo again.
As I've said before also, I feel the Snow Leopard look was the best. I loved Aqua! However no matter how much I whine and moan it ain't coming back so I have to learn to be happy with the UI I've got now and it's honestly NOT all that bad! It just takes getting used to.