While we could use some improvement, we already have one of the better offensive lines in the league. The fourth best, statistically:
https://www.profootballfocus.com/blog/2013/10/09/ranking-the-2013-offensive-lines-first-quarter/4/
Now the way the game has changed recently, four new developments have happened:
1. The teams with the best RBs never, ever win the Superbowl.
2. Teams no longer need a top defense to get to the Superbowl. (New England)
3. Teams can have awful offensive lines and still win the Superbowl. (Green Bay)
4. In this new passing league, teams absolutely cannot make it to the Superbowl without great receiving options.
10 years ago, maybe even seven years ago, your prioritization would have been right on. But as the league has evolved, or devolved as Henry points out, WR has to move way up the list.
We just can't seriously compete in a passing league without another serious receiving threat.
1. Most of last years playoff teams had legit running games.
Baltimore (SB winner) - Ray Rice
San Francisco (NFC Champ) - Frank Gore
Houston Texans - Arian Foster
Washington Redskins - Alfred Morris
Minnesota Vikings - Adrian Peterson
Seattle Seahawks - Marshawn Lynch
The other teams had elite QB play
New England Patriots - Tom Brady
Green Bay Packers - Aaron Rodgers
Indianapolis Colts - Andrew Luck
Denver Broncos - Peyton Manning
Atlanta Falcons - Matt Ryan
Then the odd ball
Cincinnati Bengals
2. NOBODY has an "elite" defense anymore. I agree with you that the league has gone offensive, but i also think a lot of the defense is based on ball control. Seattle, San Fran, Denver, Cinci, and Houston had top 10 defenses last year and GB was 11th, still top half of the league. Denver SHOULD have been in the Superbowl, but a brain fart on defense cost them, which would have meant the 2 teams in the superbowl would have been ranked 2 and 3 in the regular season.
3. Most of those teams have good offensive lines, or a mobile QB who can make up for it..
4. Only 3 of those teams have ELITE WRs
Houston Texans - Andre Johnson
Cincinnati Bengals - A.J. Green
Atlanta Falcons - Julio Jones
and I'll throw this one in there but he's GREATLY helped by Peyton Manning, but he was a legit threat with Tebow.
Denver Broncos - Demaryius Thomas
We have Garcon, and Indy has Wayne, but they're not in that top tier of game breaking, game controlling WRs.
In fact, Minnesota, Washington, Seattle, New England, and San Francisco arguably view WR as a weakness.
I agree the league has gone offensive, but the ability to run the ball and stop the run is still the foundation of being successful. A good running game can make up for a lot of things including the lack of an elite WR core.