1st) It demonstrates leadership. It shows initiative in the face of a crisis. You have the press covering him listening and asking questions among a circle of couches or a large roundtable in the WH with governors and mayors seated there giving inputs, etc. You have him doing press briefings talking about the issues and the solutions that will be forthcoming at the state level. It shows the public that Biden--and the party more broadly--are taking the issue seriously and doing something about in the face of a congress that refuses to act. This is a lot like when Gov Abbott started taking the Texas border into his own hands when the federal government did too little on border security, but instead you have a president leading this initiative and a whole lot more than just one governor involved.

2nd) Operation Warp Speed was a process that had political benefit, and it's to this day credited as one of the only productive things that came out of the Trump admin.

3rd) Just because something is a good idea doesn't mean others have thought of it or acted on it.

4th) I'm using the *example* of abortion as a unified state-level issue in absence of federal potential, I didn't say it was a popular example. You can do popular things using a model that was previously used to do unpopular things. If you want the inverse example then look at blue states passing abortion protection legislature that's ongoing as we speak. Look at the state-level marriage equality acts that were passed before the Obergfeld decision came down (in fact, these state-level passages forced that SCOTUS to take on the issue nationally in the absence of congress passing a national marriage equality bill).

5th) Some issues are national but cannot be passed as such, and in the absence of national possibilities states act. Again, see examples like marriage equality, slavery/abolition, segregation/desegregation, abortion access/restriction, etc. A lot of the time stuff has to happen at the state level en masse before it is forced to be addressed nationally.