Don't blame the Marvel guys too much. Lucasfilm had a long list of no-no's they labored under for the whole run. Bringing Fett back permanently was probably one of them. Also recall that Boba was still mysterious and cool at the time. Many fans were steamed over his lame death.
And when it was published, the EU could still be counted on the fingers of one hand, even though the term didn't exist yet. ;)