For some people, their estate planning documents are as private as their income tax returns, and nobody is ever given copies. For other people, estate planning documents are no different than a spare key to the house, and every family member and executor and/or trustee named in the documents is given a copy.
If you are the type of person who values your privacy, who does not especially trust your children, executor, or trustee, or if you have written a Will or trust which does not treat all the children equally, then it may not be a good idea to hand out copies. Also, you may have more money than your children expect, and depending on how your Will or trust is written, giving them a copy may be letting them know too much about your personal business.
On the other hand, if you have a fairly open relationship with all your children, you regularly discuss finances with them, and you are leaving your estate to them in equal shares, then go ahead and give everyone a copy. Of course, if you decide to change your Will or revocable trust, you should be sure to give all the same people copies of the new documents. If you don’t, then there may be some arguments following your death over which document controls the disposition of your estate.