First of all, there is not only one way of approaching the keys. There are a lot of techniques, and most of them are valid. Now, to my mind, it all comes down to "weight distribution". You have to be completely relaxed, always, when you play piano. I was taught and preach a lot of articulation from the fingers in pianissimo or general piano passages. You should use only your finger articulation, the "weight" from your fingers. Practice the passage with high articulation from the fingers, and just kinda let them fall... It's complicated to explain, but don't attack the piano. Use distance and weight. You will never attain a pp or ppp touch pushing the notes, I believe.
I think I didn't explain this very well, but it's almost 2 AM and I'm a bit drunk, so I should stop here.