He talked about this not really as a single person's fault (except in terms of a senior manager's failure), but as an organizational problem. He pointed out two things:
1. In particular, the organization was poorly designed, with QA being too close (in org chart terms) to production. If there's one finger to point, it's at the guy who was the common manager of both departments. And I think this is something that the engineering profession has taken to heart since then.
2. People at the time thought of things with somewhat different priorities because the context changed. At the time the mirror was being built, it was understood that the space shuttle would make it relatively simpler to fix serious problems (well, as "simpler" as any space missions could be). As it turned out, the space shuttle was less effective in that role than its initial requirements led HST management to believe. This probably led to a more relaxed attitude about the ultimate result of any problems.