I think this would be correct as no two crimes are identical. I don't really like the top-down imposition of sentencing by government, I'd prefer to see competent judges given a lot more discretion about sentencing. IMO a thug who beats the daylights out of someone for looking at his girlfriend a bit funny should get a longer sentence than someone who snaps in a domestic argument and murders their partner. The former represents a much larger threat to the public.
Which is why there is a range. What you are suggestion is that, gbh for example can be up to a life imprisonment crime.
I dont think gbh should be longer than murder though even if its a case of you just "snapped"
I think the current system is fine where you have a range of sentences for each crime set by government. Gives the judge leaway to sometimes impose a zero sentence or the maximum.
Whether you agree that these ranges are high enough for certain crimes is a different debate but you should vote a government in who believes in longer sentencing then if you disagree with it.