If one is going to store the originals anyways (i.e. the ISO images one backs up from disc), then I'd still stand by my statement, you're not saving anything by encoding it then, beyond perhaps limitations in how much storage one can keep online at a time (and in that context then, my initial statement of storage being cheap further applies, as one is saving the same content twice).

If one is just download encodes off of usenet so doesn't have the originals, and one is content with the limitations of encodes, great. But here we are talking about tools for people who are encoding their own media (and sadly, from personal experience, I consider backed up ISOs to have a longer shelf life than many of optical discs, I have media I backed up 20 years ago now that still works, while the optical discs have degraded. Hard Disks die as well, but there are effective means of mitigating that).