Hi, Valmai. I agree with your idea about playing an instrument as if the melody has meaning. I have been concentrating on that for about a year now (esp. at the piano) and it has added to the enjoyment of playing.
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There are two aspects of 'sing the way you talk.' The aspect I am interested in is not expression or accent. I am interested in voice production - how one holds the mouth, the throat, the diaphragm.

How many times do we hear a person say s/he can't or won't sing? Yet in previous decades almost everybody sang. The average person is being brainwashed into keeping silent, and I don't like it.

I think the advice to sing the way we talk might help such persons get over their fear of trying.

(There's no need to make a big deal of whether the idea is new or not. I called it 'a new thought' in my first post because it was new to me.)