Alex Davies-Jones, the minister for violence against women and girls, praised campaigning groups including the Joanna Simpson Foundation, Killed Women, and the families of the victims of the Nottingham attacks.
The Joanna Simpson Foundation, which seeks to support children who experience domestic abuse and homicide, was created after Joanna Simpson was killed by her husband Robert Brown at her home, within earshot of her children, in 2010.
The former British Airways captain buried her body in a pre-dug grave in Windsor Great Park. He was found not guilty of murder after a jury was told the couple's bitter divorce proceedings had placed him under stress.
Brown was due to be freed in November 2023 after serving half of his 26-year jail sentence for manslaughter, but his release was blocked by the previous Tory government.
Diana Parkes and Hetti Barkworth-Nanton, Joanna's mother and best friend respectively, established the foundation in her name.
Reacting to the government's announcement, they said: "We believe the government [is] squandering a massive opportunity to bring all of our archaic homicide laws, sentencing and procedures into the 21st century.
"If the government [is] intent on reform - let's do it once to create a system for handling homicide in this country that is truly fit for the future."
The pair - who were given CBEs in December - said the Law Commission report was "narrow focused".
Ms Parkes and Ms Barkworth-Nanton said they wanted the government to bring together a "broad coalition" of victims and human rights groups to examine overall sentencing and procedures.
"A failing and fragmented system cannot be bandaged. It needs cohesive and courageous reimagining," they added.