I think it was initially thought as a good idea, and possibly the other options didn't seem as good.
Why the ability is good, is it obviously ups our dps in that phase, but also increases rage generation, which is good.
Other options are:
Blood and Thunder
I think out of these options, the only other viable options would be Rude Interruption, Blood and Thunder, Tactical Mastery, and Improved Slam.
Of those, I like Improved Slam the least, because slam stops your swing timer, and I typically use up all the rage I have anyway, no need for me to unnecessarily starve myself, especially spec'd into incite for heroic strike crits.
I'm not sure about blood and thunder, because I'm not sure that introducing thunderclap into an arms warriors rotation would be beneficial. I'm sure there has been math done about this however.
I like tactical mastery, because stance dancing recklessness, shield wall, spell reflect, etc adds a lot of utility and versatility to arms play.
I also like rude interruption, I just don't think that a lot of effort has been put into analyzing it. There are a lot of raid bosses that require interrupts, and a 10% damage bonus all fight just might beat out the increased rage generation/melee swings in the last 20% of a boss fight (meaning ability to inner rage + do all other abilties).
I like where you are going though, and I think I will test that out.