Um, I may not be a fan of the Grateful Dead, but their live shows are infamous for being loose, unstructured, and spontaneous. I would hardly call them an inferior band, at least in terms of live performances.
And most bands only release 4-disc boxes, half of well-known, studio songs, 1/4 unreleased songs, and 1/4 live songs. There's no market for completely unreleased stuff, unless you're The Beatles or The Stones. As much as we like Queen, only the hardcore fans are going to buy the big box sets. There's just no marketability in them.
Of course, if Queen Productions gave a rat's ass about the fan, they would've released these ages ago.