I love my .204 Ruger for varmints. It's like a laser out to almost 300 yards. I don't see the advantage of trying to cram a 22-250 into an AR15. I love my AR's but I don't see the significant performance advantage of the 22-250 over a hot .223 and if I need to step up, I have a 6.5 Grendel or .243 WSSM in the AR platform.
I think it fits into the "because ya can" catagory. Plus lasers, lights, watches and doo-dads look silly(er) hanging off bolt guns.