Naming beneficiaries on an asset is generally very easy and has no cost. There are two major disadvantages to naming the beneficiaries as the direct beneficiaries.
First, you should ask what happens if the beneficiary dies before you. Does it pass to the children of the deceased beneficiary? Or, does the share pass to the other named beneficiaries?
Second, if the share does pass to the children of the deceased beneficiary, are the children mature enough to manage the assets? If you have a Trust for those children in your Revocable Living Trust, the asset does not ever become subject to the Trust because you have named the beneficiaries as the direct recipient of the asset.
Now, if the Revocable Living Trust is the beneficiary, you do not have these two problems.