You say Ubuntu has a bug to track the microcode package as an exception, but that doesn't seem to be having a positive effect, does it? Precisely because Ubuntu cannot pick it apart, what is it that they're trying to decide in the bug? Why is Ubuntu second guessing Intel in deciding which microcode update to apply and which to skip? How would Ubuntu know that better than the manufacturer? The Intel specification updates list tons of processor bugs including some very critical ones, so we know the microcode updates do help with some of those. When was the last time that an Intel microcode update brought a new bug or made something worse? I'm not aware of any such instance, and although that may indeed happen sometime it doesn't seem as likely as facing existing known bugs, right?
I think it could be argued that it is up to the user to decide (say, a warning during installation), or that Ubuntu could choose to apply all microcode updates by default and let the user opt out. Ubuntu might impose a certain delay, say a month or two at most, in order to see if a microcode update gets withdrawn or ends up too buggy. But I don't think Ubuntu could reasonably choose to skip all microcode updates for 1.7 years like it did in my case, or to choose which ones to apply and which ones to skip, like it seems to be trying to. Microcode should be treated like other propietary software, but with special dilligence due to its criticality. If nVidia says a particular driver release is very buggy and should be updated, Ubuntu promptly updates it. Why would Ubuntu sit on known critical microcode updates then? If, and it's really a big if, eventually some microcode update brings a new bug and Ubuntu deployed it, it would be Intel's fault and not Ubuntu's.