They also focused on defense because the two most important positions on offense that you almost always have to use a 1st round pick to get the top guys are QB and LT, and they've been covered there continuously for 20+ years. If you aren't covered there, teams almost always reach to try to find someone.
In the last 28 years, the Packers have basically used two round picks on a QB (they traded the 1992 first rounder for Favre). They only used one 2nd round pick on a QB (Brohm) in the last 28 years as well. Green Bay hasn't drafted a QB above the 5th round since 2008 (Brohm) and he's the only guy other than Rodgers they've drafted in the first 4 rounds other than Rodgers this century.
The Bears have used 3 high first round picks on a QB in the last 20 years and gave up 2 first rounders (and a third) for Cutler. A quarter of the their first round picks were invested at QB since 1999. The Vikings picked 3 QBs in the first round in that time frame and traded a first rounder for Bradford.
With the exception of 2012, the Packers starting LT has been either Chad Clifton or Bakh. Getting those guys with 2nd and 4th round picks is amazing.
The glass half empty way of looking at this is that the Packers have had the most important offensive positions covered for 28 years (QB) and 21 years (LT) and been able to invest more at other positions and didn't take advantage.