Who's deciding it's useless? I'm not even sure what you mean by that. You're making it sound like it's showing results that aren't what's be searched for.

If I search for something and it's related to what I'm searching for then it is not useless.

The service they provide is to decide that it's useless on your behalf, to save you wading through useless shit.

If I pay an offshore content farm to do content stuffing, do you want my gibberish in your results?

Then it becomes a question of which algorithm you want. Filtering out daily mail bollocks is the kind of thing that keeps me coming back to google. Am I concerned about the implications? sure; but here and now, it's doing exactly what I want.