My thoughts:
I don't think ratings should "supercede" traits, but I think they should be available only to ratings above certain thresholds and/or flesh out a player's STYLE and not ABILITY (ratings).
A guy with low STR and POW (ability to deliver tackles with force) should not have access to Big Hitter. Plus, I think that's a poor name of the trait. Aggressive (or Fierce) Tackler would be better. That's more a STYLE distinction, which is what I think traits should be for. Then low TAK and POW is taking a risk being aggressive with his tackles (which isn't necessarily hitting either - maybe this type goes for the strip instead of the tackle, the hit instead of the pick, etc).
A player can have the ability to tackle aggressively, but choose not to. Whether the player is "too nice" or simply just wraps and engages instead of trying to decapitate a ball carrier, that would be a No on the trait. His POW rating, however, should still allow his tackles to have good "stopping power" unless the ball carrier is strong, has a high TRK rating, or is able to minimize, or prevent, contact (elusiveness).
Sideline catching: I can agree that AWR (knowing where you are on the field) + CTH (ability to track the ball with your eyes and position your hands to receive the ball) + AGI (bodily control, toe tap/drag) should determine success of the pass is in reach of the target along the sideline. However, if a player loose focus in those situations or just can't "put it together" despite having the physical abilities, then I can see it as a trait and have it work like CM Hooe mentioned - if No, add penalty.
My question is then - do NFL players perform like a "No" to sideline catches would? If not, then drop the trait and let ratings alone show differential of ability.
Anyway, I basically see it as Ratings = Ability, Traits = Style/Intangibles. That way one doesn't have to supercede the other. They can work in harmony to give us a complete player and behavioral diversity on the field.
I somewhat disagree. Ratings and physics should rule success/failure and how things play out - but interaction can be as much style vs style or technique vs raw physical ability. I don't believe in always or never on the football field. I think the game is more subtle than that in almost every aspect.