I haven't studied the insurrection act, but getting Congressional approval seems like a good thing as a check on Federal executive powers. It sounds like something that can be easily abused like it's been done in other corrupt countries. America is all about limited Federal power, checks on branches of government, and freedom within the US.
Please do some reading on the Act and why it was created.
It's not about separation of powers. It's about giving the U.S. presidents the authority to deploy active duty military to maintain or restore peace in times of crisis. The Insurrection Act was invoked numerous times in the 20th century, most famously when Dwight D. Eisenhower sent the 101st Airborne Division to enforce the desegregation of public schools in Little Rock, Arkansas.
Historically, it was designed to prevent a rogue state leader (like a US Senator from that state) from raising a mob or army to interfere in matters involving the federal government. By law, the Feds could not deploy military forces against a state's forces on US soil. The Act gave the President the power to order such a deployment in certain rare and extreme circumstances.
Slavery would have likely persisted long after the 1800s had Lincoln not expanded the Act to make the Civil War legal when he sent Union forces into Southern states. We might even have remained 2 countries - the United States and the Confederate States.
In 1861, Abraham Lincoln expanded the law to form the legal basis for waging the Civil War.
Without it, he wouldn’t have had the authority to send federal troops into a state without the
governor’s permission.
After the Civil War, the Insurrection Act was further amended to give the president authority to
enforce the 14th Amendment and the conditions of Reconstruction in the South. That authority
is now found in Section 253 of Title 10 of the U.S. Code, which gives the president the right to
take military action within a state when “any part or class of its people is deprived of a right, privilege,
immunity, or protection named in the Constitution and secured by law, and the constituted authorities
of that State are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection.”
If Trump declares the
voting rights of some states's voters were violated because the state ran an unconstitutional election, ....
Since the Act was specifically created to stop states from "acting up," giving state representatives (Congress) effective veto power over Presidential action to stop such "acting up" would be unproductive. Democrat states would band together to stop Trump regardless of the validity of the action.
https://www.history.com/news/insurrection-act-thomas-jefferson-aaron-burr