Yep - that "Crown" is by design. Their intention is well founded, but in practice I've found it a little annoying at times. I don't like my stock rocking around while on the table, but it doesn't usually cause me much harm. I just have to remember that there's a crown.
I can't say i find it to be that big of an advantage. The idea is that your stock should ride on the crown and therefore always have a consistent depth. I can't say I notice any improvements, and had I paid closer attention to the packaging, I wouldn't have gotten it. It isn't bad, I just don't think it's really a worthwhile change. Flat always worked in the past, for me.