There are a few problems with Sub Excadrill that pretty much overrule the benefits.
1. Excadrill is virtually immune to status. It's immune to Thunder Wave and Toxic and knows better than to come in on a Will-o-Wisper anyways.
2. If Excadrill is running Sub, that means it pretty much can't run Life Orb which means it doesn't hit nearly as hard. Example: Ferrothorn can now check it with Power Whip as Earthquake fails to OHKO unboosted.
3. Excadrill is almost always better off just throwing out an attack or Swords Dancing.
4. Excadrill won't hit stuff like Virizion very well at all as it only has SlideQuake coverage, and it has no shot against things like Hydreigon which it actually fails to OHKO with Rock Slide without Life Orb iirc.
Excadrill just plain has better things to do than run Sub. When will you get a chance to set up and make it worthwhile? Even CB Scizor breaks your sub with Bullet Punch. No one is really statusing you thanks to the Ground/Steel typing.
EDIT:
And on a semi-related point, has anyone else noticed how standardized this meta's becomng? Everyone and their grandma runs a Gliscor(the few that don't have a Skarmory or Bronzong), just about all Tyranitar are Specially Defensive(we know all Jirachi are) and Ferrothorn is basically omnipresent. I'm not saying ban Excadrill and Latios (there's no need but they are the reason the first three are used so much) but it makes playing OU somewhat stale when so many people basically start running the same team. Sand is almost completely cut and paste and I can't count how many times I've seen Politoed/Thundurus/Toxicroak and/or Tentacruel/Jirachi/filler in team preview. I don't like ranting too much in forums but come on.
That's true but there is still room for creative teams to do well. I make a point of having at least one unorthodox set/pokemon/move on every team and I regularly make 1250+. (maybe I should stick it out and take the time to ladder but for me discussing the game might be more fun than playing it. Am I weird? idk) I honestly think that halting the suspect testing process was good for the metagame because it gave people more time to adapt to threats and also gave them more time to be bored enough and use different teams. This, along with the #dreamworld challenge, is helping to diversify player strategies a bit more as people have more time to experiment rather than "RUSH RUSH SPAM STANDARD TEAM TO REACH REQS"
Oh, and one more thing: Creativity helps, not hinders, as standards are prepared for more.