The paper on 120 rolls of film is there to protect the film from light. There is no cannister or anything else, just a rolled up film, with paper.
Yes, a cassette would be another solution to the problem.
But 120 film is very old. People didn't care in the same way about convenience then as they do today. After all, it (120 film, no cassette) works quite well, doesn't it?
Since the film needs to be protected while being loaded and unloaded, 220 film only has paper on both ends of the film, wrapping both beginning and ending of the film light-tight.
No paper, means smaller diameter of the roll. Which in turn means there can be more film on a roll and not be wider, i.e. still physically fit in a magazine designed to take 120 film.
So 220 film has twice thelength of 120 film, which, of course, means twice the number of frames too.
Of the two, only 220 film works with vacuum backs. That's why the Contax 645 vacuum back takes 220 film only.
And yes, the larger the film, the more it will benefit from some means to keep it flat in the film gate.
There are, for instance, LF film holders available that have a "sticky tape" like adhesive covering. Large format aerial cameras use vacuum plates too.
However, we have managed quite well for many years with 120 film and without vacuum backs, haven't we? So it must not be a problem desperately in need of a solution (like vacuum backs), right?
;-)