Using this definition, is it good for a nation to have a sizable class of permanently wealthy?
Yes.
Yet another misunderstanding of the real world. Read a copy of "The Millionaire Next Door". People who earn their wealth understand how it was produced. In general, those who inherit wealth from a prior generation fail to hold on to it for more than one or two generations. The reason is that they don't understand how it was generated. It doesn't take government interference with estate taxes to destroy or confiscate the wealth created by a given generation of a family.
The travesty of estate taxes is the way it causes family farms to be sold for taxes. Families are unable to continue farming a piece of land due to the greed of the socialist politicians. The farms are frequently turned into nature conservation preserves, developed with houses or snapped up by a large corporate agricultural entity. The farmers are hardly "rich".
I pose a similar question to you: is it good to import an endless flow of uneducated and unskilled people from all over the world to live on the dole? There is an endless supply of people who would love to come to this country and sit on their asses while the taxpayer cares for their every want and desire.