A purpose of death taxes is to even out the effect of not being born into wealth. I'd rather make it easier for living people by 'punishing' dead people than make it harder for living people by punishing them for not being born into the right family.
I absolutely see your point, but if you set inheritance tax higher than gift tax rate, then that rate difference does nothing for wealth inequality (because people are just gonna gift things in their 80's at the latest, or set things up legally to avoid the tax), while the inheritance tax is highly punishing for families of the unepxectedly deceased.