Yes the offensive line was mostly fine during 2010. However, offensive line is a position of need in 2011 and especially in 2012. The Mankins situation doesn't sit well, and the team does not have a starting left tackle in 2011. Koppen is aging, and Connolly isn't a starter. Protecting the team's $20-million star QB should always be a top priority.
Front seven edge players are also a position of need in 2011 and in future years. However, the value and talent of players at these positions dramatically decrease from picks 1-10 to everything else. In addition, players at these positions historically have a higher bust-rate than offensive linemen. The drop-off between a top ten offensive linemen versus a late first offensive linemen isn't as great, and the value is still there.
A 2-gap DE that consistently draws the attention of two blockers immensely helps the pass rush. A player like this, in my opinion, provides a better foundation upon building a pass rush than a situational pass rusher (a la Seymour versus Clay Matthews). A player like this also allows for more variety and unpredictability in blitz schemes and coverage disguises. Wilkerson, Watt, and Jordan are players that potentially fit this mold. Selecting a DE at #17 and an OLB at #33 addresses the 'pass-rush' deficiencies in two different ways.
Miller is a top ten pick. Quinn is a top ten pick. Smith may fall to 17, but many scouts and 'experts' feel that he should gain weight and play as a 43 DE, or become a situational pass rusher. A situational pass rusher is not worth the economic constraint tied with a first round pick. In my opinion, the 'Willie McGinest' type of 34 OLB will not be found in the first round of this draft, and neither will a Richard Seymour (maybe Dareus). I do think Watt, Wilkerson, and Jordan have the potential to have a career similar to Ty Warren.
Mike Reiss has written a few times in his blog that drafting a situational pass rusher in round 1 should be considered because of the percentage of sub-packages the Patriots have ran in the past two years. I disagree. I believe this is a consequence of not having ideal 2-gap DEs or 34 OLBs that can play on all three downs. The Patriots defense, and most other 34 schemes, are predicated on versatility. The Patriots have lacked players with the adequate versatility, and as a consequence, they are in a sub-package 50+% of the time. I don't think BB wants to do this.