Yeah, there were a lot of things that Congress and the Executive branch did in the aftermath of 9/11 that seemed necessary at the time that may not stand up to the scrutiny of history.
I personally think the framework of the War Powers Act would be a good one if it had a bit more teeth in it for Congress. The immediacy of world events today makes the ability of POTUS to act quickly/decisively extremely important, and I don't think we ever want to limit that, but that must be followed up with a deliberative process between the two branches of government.
The fact that the language in the 2001 and 2002 AUMFs was incredibly broad has not been helpful in finding the right balance on war powers.
Congress rescinded their own Constitutional authority. If they want it back, they simply have to pass a new bill (most likely with a 2/3 majority to override the inevitable veto). They don't want it though because Congress is largely populated by career politicians whose safe space is to avoid making a decision on anything as an out to take whatever politically convenient stance on issues come election season. Also see: the annual budget 'crisis' due to indecision.
With modern communications technology, I can't imagine a situation where the President would have to act before Congress can vote for an authorization of force. That should take an hour at most, and they could even do semi-annual drills to practice such measures.
Besides, unit self defense doesn't require Presidential authorization.
PS: Before anyone misconstrues my post, I think it's a good thing that we got Soleimani and the President was within his authority to make the call the way the law is currently constructed... but I think it's possible to get to a state where the President has to get Congressional authorization before doing so.