Besides. Math says that a +1 is important, but if that were the case, then Careful Shot/Sure Strike would be a significant power boost. They are, after all, providing a +2. Considering the amount of complaint that they are underbalanced or less important, would show that's not the case. Just because we are presenting averages does not = common play experience.
Cadfan, using your argument, grind would be decreased if the ranger relied on Careful Shot and a fighter relied on Sure Strike. But the two continually using those powers would still contribute to grind. Everyone standing around spamming the same attacks isn't going to make the fight more fun, and that goes for those powers that grant +2 to attacks.