There is a big difference between having a mature and healthy discussion about the reality of an eventual estate settlement and kids being irresponsible with their own financial planning.

Inheriting a few bucks from an estate could very well be managed as a nice surprise.  On the other hand being handed an unexpected six figure+ sum for some people could cause problems if they are aren't used to managing money.  Ideally potential issues should be discussed at the same time to ensure that the kids are in the best position to benefit and properly manage the inheritance.  At the same time obviously the kids need to be mature and rational enough to understand that things could change in the interim.

My own personal take is that parents should disperse surplus assets over time when their kids and grandkids could make better use of the inheritance.  Things like house down payments, RESP contributions, business startups etc.  Both parties then get to see the benefit at work.