Files are a very bad unit to elevate in importance, and number of files or file size are really bad proxy metrics, especially without considering the statistical distribution of downloads (leave alone the question of what is more "important"!). Eg: Junk that’s less than the size limit is implicitly being valued over good content that happens to be larger in size. Textbooks & reference books will likewise get filtered out with higher likelihood — and that would screw students in countries where they cannot afford them (which might arguable be a more important audience to some, compared to those downloading comics). Etc.
After all this, the most likely human response from people who really depend on this platform would be to slice a big file into volumes under the size limit. Seems to be a horrible UX downgrade in the medium to long term for no other reason than satisfying some arbitrary metric of legibility[1].
Here's a different idea -- might it be worthwhile to convert the larger files to better compressed versions eg. PDF -> DJVU? This would lead to a duplication in the medium term, but if one sees a convincing pattern that users switch to the compressed versions without needing to come back to the larger versions, that would imply that the compressed version works and the larger version could eventually be garbage collected.
Thinking in an even more open-ended manner, if this corpus is not growing at a substantial rate, can we just wait out a decade or so of storage improvements before this becomes a non-issue? How long might it take for storage to become 3x, 10x, 30x cheaper?
[1]: https://www.ribbonfarm.com/2010/07/26/a-big-little-idea-call...