It is difficult, as both races are cool mechanically, but dwarves seem to have some sort of identity whereas Half-Elves not so much - and it's easy enough to run a world where children of mixed race unions take after *either* mum or dad - so you can have an elf child or a human child, though the human child may have a longer life span.
Then you get into the weird ones where for example, what do you do with an elf/Orc child? An Erc? An Olf? What about a drunken encounter leaving you with a Quarterling or a Gnelf?
This is all Elrond's fault.