Lots of good stuff here. I agree with all but three points.
1. Detroit's offense as a "one trick pony." This has been a talking point for Seahawks fans and Seattle area media but is not accurate. The Lions have been heavily investing in their passing game and have complemented Megatron with four other offensive playmakers drafted in the first or second round the last few years. Unfortunately, all four of these players currently have higher trade value than any of our receivers when it comes to value per contract dollar. If you think the Lions passing offense is a one trick pony then our passing offense must be a zero trick pony? Detroit fans love the potential of their youngsters even though they have yet to show up in terms of production. Boy, does that sound familiar.
You mentioned TE Brandon Pettigrew (2009 1st round pick). He had a couple of huge games last season and will probably get the bulk of the looks that would have gone to Burleson. He is not just tall (6'6") but strong as well (265) with the same measurements as Gronkowski, and is used effectively as both a blocker and a receiver. KJ Wright's size helps here he will still be giving up both height and weight.
Detroit fans see WR Titus Young (2011 2nd round pick) as a much better version of what we saw Lockette as. Really quick off the line of scrimmage and very fast down the sideline. They worry about his hands and his ability to deal with getting jammed at the line, but are optimistic that he can run away from our bigger CBs for TDs if he ever gets off the line cleanly.
WR Ryan Broyles (2012 2nd round pick) will be taking over for Burleson and fans are excited to see what they have in him. He is coming off an injury and was inactive at the beginning of the season, but he played well coming off the bench for Burleson against the Bears. He will likely see action as part of the 3+ WR packages and be paired up against our nickel or dime back. That fits his apparent skillset perfectly which is finding the hole in zone coverage with quickness and good vision. This should be a fun matchup to watch as Tru becomes the wily veteran facing a quick but raw rookie.
RB Mikel Leshoure (2011 2nd round pick) is also a threat in the passing game. He has good hands and quickness and can get upfield immediately after a catch. He fell to the bottom of the second round due to character concerns, but would likely have been a late first round pick otherwise. On first and second down he has some similarities to a Lynch-Lite; a power back who keeps his feet moving and thrives on YAC. However, the Lions see Leshoure as a back that can stay on the field on third downs.
This is a talented group headlined by Calvin Johnson, not a group of scrubs with Calvin Johnson as the lone star as the overly simplified narrative would have you believe.
2. As you say, part of our success when it comes to passing on first down is that teams are expecting us to run. However, I do not understand why you view this as a persuasive argument for passing more. Passing more on first down would change the expectations, and thus lower the expected value of attempts. There may be other good reasons to open up our passing game, but success based on infrequency is not one of them when you are advocating for increasing the frequency.
3. I agree that the penalty situation has been much improved, but the discussion needs to look not just at total penalties but at the type of penalty.
Okung's false start in the fourth quarter pushed us almost into our end zone. That made an impact on what sort of plays we could call and reduced the chance of success significantly. His hold in the second quarter turned a third and and short in 49ers territory into a second and long in Seahawks territory which resulted in a punt. While I would rather have a hold than a sack, this came on a running play where Turbin had room on the right side and would have only been minorly affected. Both of these fall into the category of bad penalties, as they could have been avoided by better discipline and the reward did not justify the risk. I am fine with the occasional contested pass interference call or holding call that prevents a sack, but a single bad penalty is one bad penalty too many.