While he doesn't have STAB on it, Steelix also picked up Rock Head Head Smash, along with STAB Meteor Mash / Gear Grind and Shift Gear, and the ability to lay Spikes. Surprise, Steelix is a sweeper now?
EDIT: Also, just read the Landorus-I overview on the OP - even with the Sheer Force boost, Air Slash is only 97.5 BP and now has no secondary effect. Aeroblast remains the superior option outside of rain with 100 BP, the same accuracy, and a higher crit chance. And even outside of rain, I think most people would be willing to forgo accuracy in favor of a 156 BP Hurricane.
EDIT2: Back to Head Smash, while Rhyperior may not be able to run Rock Head, both he and Rhydon learn Reckless. Rhyperior is probably more suited to this due to his higher Attack, and the fact that he doesn't focus on defenses as much. Reckless Head Smash is 180 BP before STAB, coming off of 140 base Attack? This hits harder than Rampardos' Head Smash.