A lot of the problems are already solved by probate/estate/etc.

Like, if you had property at a bank, you'd need a death certificate which you'll have requested tons of if someone you loved died... along with potentially some sort of proof that you were the rightful heir (Worst case, you'd establish this through probate, likely going to end up being a simple document). This would be more overhead for steam, but usually not complicated documents once everything is settled. As for splitting up the account, your steam account would probably be classified as a singular item and any attempts to break it up in a will would likely just end up being void.