Two reasons I can think of are:
1) To prevent boot out with three pin bindings mounted flat on narrow waisted skis; and
2) To give greater hold (4 hole riser) for three pin bindings with three screws.

Which boot do you have? I recall posts on social media to the effect that some Crispi boots are out of spec on the distance between the pins and the end of the duckbutt.

My wife is 5 feet and 100lbs and manages the Traverse just fine in a 169. Her previous ski was a Rossignol BC 70 in a 170, which she hated due to the crappy waxless patterm

Which probably steers you toward a 75mm boot and binding, due to the width of those skis. A basic three pin binding would be fine, but cables give you a bit more control on the downhill. However, i get the sense you're basically more into "straight ahead" k and g. I would recommend the Rottefella th...

The goal is to use the skis as a snowshoe substitute That to me says you should look at a Hok, or for more skiability a Kom.

To answer one question, the cable (rods) can be easily removed from the Rottefella 3 pin cable binding.

I picked up my boots today from MEC, they were on sale for 40% off so I couldn't resist. First Impressions: they seem very comfortable out of the box, much better fit than my Alico Ski March, which are wider. I mounted my Spike Lite Dogs on a piece of 2 X 4 to try the boot and it clicked in nicely. ...

You know, I suddenly remembered a post from the halcyon days of Mitch's Telemarktips, when Bob Mazerei (a telemark legend) posted about skiing some wide alpine skis with NNN BC bindings. So maybe it can be done if the snow is soft, and you ride the skis rather than drive them up on edge. I'm too old...

Norseman in Calgary sells Asnes.

What you might want to take into account Garth, is that Voile warns against mounting freeheel bindings on their Hyper series due to the light Paulownia core. However, there are reports from a few freeheelers on various sites that they haven't had any issues skiing them with tele bindings, but maybe ...