Speculating a bit more on the Steelers common practice of drafting QBs, lets look at who they could have taken instead. Yes, I know this is a thin argument and playing the could have/should have game is a bit weak, but I'm just illustrating a point that taking a QB just to take on -- even in later rounds -- can have a negative impact.
I looked at these drafts and picked players who were taken within 10-15 picks of that QB.
2008 Kellen Davis TE, Carl Nicks OG
2006 Delanie Walker TE, Laurence Vickers FB
2004 Rothlisberger was clearly the best option there.
2003 Dan Koppen C
2000 Mark Bulger QB(yeah , I know

but shows what a crapshoot evaluating is ) , Dhani Jones LB
1996 Marco Rivera OG,
1995 Kordell was a good pick, but Curtis Martin was available.
1994 Lee Woodall LB
1993 Pretty much just other QBs here in Elvis Grbac and Trent Green
1992 no one but it's 12 round at this point.