I want unlimited days history retention because I have many notes that I only edit once a year or two or three. It's even more important to have history for these because my memory is unlikely to be clear.
However I also have a lot of notes that I edit all the time that I don't need much history for. It's kind of a waste to keep a bunch of churn forever.
With unlimited history or even just very long history sooner later a body is likely to want to trim it. That brings up a host of challenges on how, especially if it's a note by note or notebook basis.
An alternative that I think would work for a lot of folks, myself included, is to tell history to keep number of revisions instead of days.
Related feature request: Note History