There are many problems with the arguments against a $5M inheritance tax (BTW: I speak of first hand experience as a 0.1%-er and I'm personally ambivalent about it.)
Argument 1: Family businesses will suffer.
(a) Firstly, a surviving spouse can receive an unlimited transfer and the estate tax does not apply. Other family members involved in the family businesses can and should receive their own stakes in the business rather than waiting for parents to die, especially if they are active in the company. If they're not active, they could still have a stake before death but it's also less of an issue because they don't deserve as much concern as active family members about having to sell the business (they would probably just sell the business anyway).
(b) A trust can also be set up before death and assets transferred to it.
(c) Term life insurance can cover any gaps.
Argument 2: Family homes will be lost.
Again, spouses can typically keep homes because of the spousal exemption. Parents of children should take out term life insurance. That basically leaves the homes of unmarried/widow(er)ed older people. Those homes can be treated like any other assets in the estate and may be sold off if necessary. In the occasional scenario that a child wants to move into that house, there are plenty of other issues such as buying out other siblings. Again, life insurance can cover all this.
Argument 3: Double taxation.
As several others have pointed out, we are subject to multiple taxation at many levels.
Argument 4: Greedy government.
The government has a budget and should strive to balance it. Generally, the money has to come from some sort of tax or spending must be reduced. It's just not realistic to cut government spending by 2% when almost all spending is "off-the-table" before such negotiations ever start (e.g., Democrats nix cuts on social spending, Republicans on military spending, farm subsidies -- but many more). So, if it's not this tax then it's got to come from through some other tax. I think most of the people fanatically against the estate/inheritance tax are just anti *any* tax so their arguments sound similar to arguments in every other discussion about taxes. They seem to forget that we already have the lowest effective tax rates as a share of GDP for 60 years (http://economix.blogs.nytimes.com/2011/05/31/are-taxes-in-the-u-s-high-or-low/?_r=0).
BTW: I've got no problem with the fairness of estate taxes in redistributing wealth. My main issue with this tax, like many things related to personal taxes (as opposed to the simpler corporate tax laws), is the cost of managing all of this, both in terms of the cost to the individual and the cost of collection by the IRS.
BTW2: I am neither a democrat nor a republican nor a libertarian. I take every issue at face value. On any given issue, I can agree with one side or another or neither.