Quark's postmortem comes up a lot, having been in the publishing trenches I see it differently: Quark bet heavily on interactive CD-ROMS as the future, not the internet. They developed cross-compilation from print to interactive CD-ROMs. In a betamax vs. VHS war, the interactivity of CD-ROMs lost to the horrible and graphically disastrous web 0.9beta. Somehow this is forgotten when gurus want to classify every business story according to pet-theories of success and failure. Could you be betting on the wrong future?
Having been around when Quark started to fall behind and then switching to InDesign myself, I don't agree with you. QuarkXPress was crap, and Quark had no interest in modernizing their software. It took forever just to get native OS X support, and the software lacked a lot of InDesign's print publishing features. Desktop publishing has always been a Mac-centric affair, and ignoring Mac users was a pretty poor decision.
Quark tried to milk its customers dry. It did and then they moved on. They never diversified their company, and the one product they made was becoming despised.
Final Draft is a good modern-day version of QuarkXPress.
A quark user could smoke an InDesign user, mintues vs hours. High pressure, high speed design is still not matched by InDesign today. But there is very little high speed design left. Of course, InDesign is wonderful now.
Had it gone that way, they would have been slaughtered by Macromedia's offerings (Authorware and Director). And Macromedia somehow managed to "shock" their tech onto the web when the little disks mostly went away.