Because on a superficial level Iyun separates those that ‘can learn’ over those that can’t. So everyone including the RYs themselves want to excel at this particular aspect of learning. Imagine a Yeshiva that excels in Bekius rather than Iyun. It would simply have a name for catering for less gifted students that can’t handle deep stuff like R’ Boruch Ber or R’ Shimon.
Like I said in my previous post, if you have a good head you can excel in Iyun pretty quickly with not much effort. However to become proficient in Shas takes long and tedious hard work. And our generation is not geared up for that. The accolades don’t come quick enough. That’s my humble opinion.