The issue of corrective disclaimers is especially important right now, given the volatile nature of tax laws in the U.S. You can't know what the circumstances will be when it's time for your survivors to figure out your wishes and untangle your will, so it's best to plan ahead with this in mind.
For the beneficiary, it's also important to remember the financial environment. For example, we used to think that an estate's executor should sell off all investments -- or at least diversify them -- in order to make splitting up the proceeds easier on the family. This was simple, because the worth of investments was calculated and taxed on its original cost.
But now the rules have changed, and we pay income tax on the difference between the two -- which makes it the executor's problem, if we don't consider this fact. The IRS may even assign a starting worth of zero if you can't document the original price, making the whole value one big piece of income. That's no way to treat your heirs!