Why? Stop government theft / misuse / abuse of taxpayer funds under false pretenses. Stop government's erosion of the United States Constitution, as well as flagrant and frequent abuse of power against the people.
ICE is now a far bigger threat to America than undocumented immigrants. It's an experiment of, and prelude to, implementing Stalinist persecutions under the color of federal law.
Even if one doesn't know anything about the type of people who have actually been running this country, one can still see the unmistakable pattern of systematic, step-wise destruction of Constitutional protections of liberty and freedom in America.
I support immediate abolishment of ICE.
PS. I'm in favor of instituting criminal investigations and charges against Hillary Clinton (along with a couple of former US presidents) as well as impeachment proceedings against Donald Trump, even though I know that neither is going to happen. The monkey show in Washington DC will go on.