Re: My uninformed comment
> We'll start with the problem that it's designed for optical media.
No its not. Its designed for a variety of media types. I use UDF a lot and can safely say that it has modes for optical and HDD. Perhaps you should read the page again and you will see that it has specific formatting modes for HDD's and anything that works like them.
Most of the development between versions focus on optical media because there was so much improvement to be had in handling wear levelling etc.
> As in media that can be written a couple of times at most
Lol, hundres of thousands of writes are a couple of times? I know of SSD's that can only handle a few thousand, what say you about those?
To summarise the rest of your comment: UDF is a file system that would have given us everything we would have needed. It was borked by the companies (M$) that want a monopoly on file systems use, with as you say, poor implementations. Thus, like other borked formats like RTF, UDF has basically been beaten up and left in the gutter to be used by those who need its features and dont mind dealing with the vendor implemented incompatibilities.
What other open and free filesystem can you think of? Its not FAT, yet thats on all SD cards and flash drives, its not NTFS, not HFS+. EXT(1,2,3,4), XFS, ZFS etc all meet this definition but guess what, you dont see them, even though they are superior, on large flash drives.
If this exFAT thing allows a Free SOftware exFAT driver to legally exist, maybe this will be a good thing.