Maybe I don’t understand your question very well, but a limitation of a footnote area makes a lot of sense. A footnote is a note which adds some explanation to a word or part of a text on page. If you increase the footnote area to - let’s say - 90% ,you only have 10% of a page for text and 90% for footnotes. I feel that in such a situation it might be better to reconsider the content of your relate paragraph or chapter.
My experience with up to about 10 footnotes per page is that the automatic height adjustment work very well.
My setting is: Format > Page > Footer > Autofit height is checked.