Assume that inheritance taxes were raised: Why would anyone be incentivized to work more since their kids won't get any of it.

Destroys all incentives to work more. People will just move to countries/states with less tax.

There is a long distance between a 0% and 100% rise in a tax.

It sounds like you are saying the only reason to work is so that your children will never have to work.

Also will the government spend an inheritance better than a person’s children?

The median inheritance in America is $7000