They are altering the content of a copyrighted work and selling it.
That would be like Michael Moore taking Ann Coulter's book, removing what he didn't like, possibly adding what he does like (I realize these companies don't add, but altering is adding or subtracting) and selling it under the same cover.
We can't be for altering a copyrighted work in a way we would like but against it if we don't like it. I agree these companies are providing a fine service to consumers and it's unfortunate that Hollywood doesn't embrace it, but I don't see that they will win on appeal.
The only way around this for families is for individuals to procure the same editing software, purchase the unredacted movie and edit it themselves, for private use. This would be akin to Michael Moore reading Ann's book with a Sharpie in hand and removing offensive content. So long as he doesn't sell it, he can edit it however he wishes. He, and the editing companies, simply can't sell someone else's work in an altered state.
Here's a secondary source that explains your point.This is the kind of detail I was looking for.
The Exclusive Rights
A copyright owner has five exclusive rights in the copyrighted work:
Reproduction Right. The reproduction right is the right to copy, duplicate, transcribe, or imitate the work in fixed form.
Modification Right. The modification right (also known as the derivative works right) is the right to modify the work to create a new work. A new work that is based on a preexisting work is known as a "derivative work."
Distribution Right. The distribution right is the right to distribute copies of the work to the public by sale, rental, lease, or lending.
Public Performance Right. The public performance right is the right to recite, play, dance, act, or show the work at public place or to transmit it to the public. In the case of a motion picture or other audiovisual work, showing the work's images in sequence is considered "performance."
Public Display Right. The public display right is the right to show a copy of the work directly or by means of a film, slide, or television image at a public place or to transmit it to the public. In the case of a motion picture or other audiovisual work, showing the work's images out of sequence is considered "display."
Infringement
Anyone who violates any of the exclusive rights of a copyright owner is an infringer.
Example: Developer scanned Photographer's copyrighted photograph, altered the image by using digital editing software, and included the altered version of the photograph in a multimedia work that Developer sold to consumers. If Developer used Photographer's photograph without permission, Developer infringed Photographer's copyright by violating the reproduction right (scanning the photograph), the modification right (altering the photograph), and the distribution right (selling the altered photograph as part of the multimedia work).
http://library.findlaw.com/1999/Jan/1/241476.html
Note that it all boils down to use "without permission". I'd like to see the language in the agreements between the producers and the vendors. There may be a colorable argument that permission had been granted.