My 2 cents: I find sway control an absolute necessary and do not use it as a crutch. Even with the sway control I am very careful when I tow. I find it particularly important when I'm passing or being passed by large trucks.
I've seen many RVs on the side of the road (in person and on news stories) flipped over and destroyed. An accident caused by out of control sway RV is usually devestating and sometimes lethal.
I see similarities between sway control in towing and anti-lock brakes in a car. How many lives and accidents have anti-lock brakes saved since they were placed on cars? I know anti-lock brakes have saved me a few times from losing control and getting into accidents.
Keep in mind that just as there are automobile drivers of all experience levels, there are also RVers of all experience level. So just as anti-lock brakes can prevent accidents, anti-sway can prevent accidents. You can call it a crutch, but I look at it as an insurance policy. And I have a lot less white-knuckle driving experiences because of it.
And don't tell me the big rigs don't sway. I've seen them on the highways during windy/gusty conditions and they have a difficult time keeping everything between the lane lines!
And it isn't like anti-sway control is that outrageously expensive. So to me it is a no-brainer.
