Making a Will is not about wealth it is about making sure that what you want to happen to your estate does happen. It gives you the opportunity to specify such things as who will administer your estate, who will care for your children and who will receive specific items of your property.
There are likely to be cases where the effect of the old rules still applies due to the age of the will. The case of Timothy Everard Upton v National Westminster Bank, Richard Tichborne Everard Upton and Rosalie Jane Prior (2017) is an example.
A grandfather made his will in 1930 and left three-fifths of his estate to his son who in turn purported to leave it in his will to his illegitimate son whom he had adopted during infancy. The son died first. The son's executors disputed the child's claim to his father's share of his grandfather's estate on the grounds of illegitimacy. The court held that the reference to 'a child' in the grandfather's will was a reference to legitimate children.
No contrary intention appeared in the will. The provisions of the 1987 amendments were not retrospective. The share of the grandfather's estate which his deceased son would otherwise have inherited therefore passed to the surviving son and not to the deceased son's child.
Note: This case turned on the issue of illegitimacy.
You may be puzzled as to why illegitimacy was an issue if he had been legally adopted by his father. Unfortunately, the Adoption Act 2006, which would otherwise have enabled the grandson to inherit, was not retrospective either and did not apply to documents executed prior to 2006. See http://www.education.gov.uk/childrenandyoungpeople/families/adoption/b0067811/adoption-legislation
It has to be said that the potential existence of illegitimate children can be a nightmare for executors. If a testator leaves a gift to his children, how can they be sure that there are no illegitimate offspring in existence? It is kinder to them to name your children. Instead of a gift 'to my children' write 'to my children Fred Mary and Jane'.
They may then safely distribute to the named beneficiaries without worrying that the description 'my children' extends further than your relatives knew.