FKs were nerfed and Corners probably should be and will. (Seems like deflections which result in a goal got a boost recently.) The rate is not as high as you suggest but CK conversion rate is too high for real life comparisons......but its a game so I don't care that much how it compares to real life.

But, more importantly, if most CKs were not converted they'd soon be dropped from commentary as inconsequential. So most of the ones we 'see' would be goals and it wouldn't change the feeling that when a corner makes the commentary there's a good chance there will be a goal. So what would be the point.