Late to the party (well, over here anyway ^^), but I definitely agree with @DiapDealer that KU should absolutely not add stuff that wasn't there in the first place.
The fact that the Kindle framework can't deal with an ASIN-less KF8 properly is a bummer, but, well, out of KU's scope, I think? (KU is just doing its job, if there's an ASIN in the source file, there'll be one in the output ones).
Because after all, why the framework just craps out in fun and interesting ways with ASIN-less KF8 files instead of choosing to generate a md5 hash like it does for ASIN-less M7 or dual files is kind of a mystery...
It's just one of those quirks that one should be aware of when dealing with that kind of stuff. Which is why I'm happy to see that this plugin *does* have a way to handle it seamlessly

.
So, yeah, maybe add a spiel to the relevant setting somewhere about how brokenly the Kindle (well, FW 5.x at least) handles KF8 files if there's no ASIN set, but that's about it. Can't make too many assumptions about what people will do with these files, after all

.