I'm not sure it is/was the snowplow that is the root of the problem that causes people to cling to a "bad habit". I do think the concept of the "comfort" that the position provides is where people get stuck.
Years ago I started thinking about the relationship of the three major skills of pressure/edge/steering (meaning leg rotation) (P/T/E) and how to blend them for each specific turn. Years back when the gear couldn't "deliver" as it can today we needed far more (leg) rotation to get the ski turning than we do today. The traditional snowplow provided us with this in a static way so all we had to do was increase pressure on one side to go to the other. Edgeing was natural because of the width of the stance.
Today the equipment is so refined that the ski can turn almost by itself if edged minimally with a little pressure on it. Therefore we no longer need the wide stance and braking can be accomplished by turning across the hill.
Some thoughts to ponder.....The more you attempt to use the skis to control your speed the tougher it is to turn. So it's easier to turn in a gliding wedge vs a braking wedge vs snowplow.
From a skills standpoint here edging more makes (leg) rotation tougher.
A never met a move I didn't like ! As Ott said why throw out anything ? We do however need to adjust the percentage of pressure/edge/steering to alter anything in our own skiing.
Flaws in our skiing are a direct result of incorrect relationship of the three skills in any given turn.
I don't agree with this whole "negative move" theory. There clearly are better and worse ways to accomplish a given turn, but if both work.....where's the negative.
Adjust the percentage of P/T/E for a given turn and this "negative move" can become a positive move.
I'm sure I use snowplow, braking and gliding wedge every day I'm out on the hill
Avoid with a passion teaching the snowplow or braking wedge till a student has a firm grasp on their turns (wedge christie perhaps) the jump right in and teach a snowplow. You may have someone who in the future may need a sudden stop in a narrow maze or a future patroller in the group. You shouldn't short change them !
Think of the relationship of P/T/E for any given turn and change the percentage of each that you use in that turn and the turn itself will change.....hopefully for the better