Combines can cost on the high end of 6 figures. Under the old exemption, one of those would take up the entire exemption.
By the way, you are making some valid points, and setting aside other issues, I can see why you might think that $5M is sufficient exemption for any inheritance. While I'm not sure this is political hill I would choose to fight on first, or even die on, I do admit to working hard to pass wealth on to my kids, and my default bias is "hands off" when it comes to the government taxing anything I might want to give my kids. I perceive that as an attack on the family unit. There should be no taxing on transactions between family members. If an inheritance leaves the family (the case Lehigh raised), then I'm less opposed to it being taxed.
Also, can you explain your 11 million number? Are you assuming that parents die separately, and own property separately, and bequeath separately, and so have separate exemptions? This is an honest question.
If one spouse dies, and the intestacy laws give the property to the second spouse, who then dies, the exemption is $5M applied in succession (that is, anything over $5M is taxed twice...after having already been taxed as income...and in some cases after having also already been taxed under capital gains laws if it is stock, for example).