Articulation sounds mechanical, and the tone is not sufficient. Currently, most pianists agree that an integration of finger motion and wrist and forearm movement is necessary to produce a full, open sound without tension. Emphasis on relaxation, particularly focused on the forearm, and use of the body's natural arm weight transmitted through a low wrist is often advocated to ensure that the fingers play deeply into the keys. The shoulder should be entirely relaxed and used. Obviously, an uncontrolled drop of the arm does not contribute to controlled sound.
Pressure is balanced by relaxation - neither is absolute.
Transfer of arm weight onto a finger is followed by a release of pressure, preparatory to moving to the next note or chord. Relaxation at the piano is not a total surrender of control over the muscles. It involves responsiveness on the spur of the moment, to maintain musical as well as technical continuity. My mentor and greatest influence is the noted author, composer and pedagogue, Seymour Bernstein. He points out that once you consciously induce contraction in a muscle, you can begin to learn to relax it consciously.