The analogy is a bit flawed and not really comparable in this situation, simply because you cannot compare wing length in flight to a-arm length on the ground.
Have you ever seen an air race airplane? Large engines with relatively short wings for high speeds and tight turns. The short wings necessitated much higher speeds to maintain the lift required for flight. The wide body and short wings creates a centralized mass center for quicker maneuvering.
Compare that to the plane that circumnavigated the globe. Both are prop driven aircraft but the later operated at a much slower speed, using a much larger wingspan for additional lift at that slower speed. A similar concept is used when an aircraft takes off “into the wind” as the air speed is traveling that much faster over the wings to create additional lift, while the ground speed of the aircraft is reduced compared to if there was no wind, or it was taking off “with the wind”.
Back to the widening kits……Modern race quads or custom chassis with a single rail up front, do this for handling and for additional wheel travel. The kit’s inherent flaw and sole base of the reasoning behind it is that the A-arms pivot points are moved outward for additional width, but the tie rod pivot point at the stem is not addressed. There is no explainable gain in wheel travel, the kit only adds additional width. The “narrow frame” allows the A-arm pivot to be almost directly in line with the tie rod pivot, Polaris used a similar idea with their PRO steering setup which really works. They moved the tie rod pivot outward keeping the A-arm pivot inline to reduce steering deflection throughout the travel (bump-steer).
The other benefit of a “narrow frame” allows for additional length in the A-arms. Simply put, longer a-arms means more wheel travel. Your wheel is at the end of a lever, maintain the pivot point and extend the lever and the wheel will move farther vertically in relationship to the angle of the A-arm. That’s why an I-beam, TIB or TTB, is popular for use in the desert. A longer lever allows more travel; of course there are other factors that I’ll explain if anyone is interested….with an F-150 as an example popularity dictates 96 and older, 97-03, then 04+ Beams on a 96, Fairly long A-arms on 97-03, and then the 04+ uses fairly short A-arms.
With all of that said, the only terrain I would use one of those kits would be flat with minimal suspension input required where additional width would have a benefit. Flat track or Ice racing are the only ones that come to mind. A true TT track is a bit rougher and in my opinion uses more suspension travel than flat track or ice racing.
I can add some drawings later this evening to give a visual of the lever reference if need be.