I've just always played w/ GM's who ENCOURAGE the players to plan & plot privately, w/o the GM's knowledge. So suddenly having the GM able to read the private conversations goes against what I've always done & known. Yes, I know you can do it other ways - Yahoo IM, PM in roll20, etc, etc. But while playing, whisper is the easiest/quickest and shows up where the player is most likely looking. Don't get me wrong, I do like having them logged, but only logged where the people who could originially see them can find them.