To take the contrarian view...
Suppose someone was able to explain the physics involved in the operation of such craft.
From a) coming up with a hypothetical explanation, or b) dismantling one and analyzing it?
a - is what any armchair ufologist or CalTech student can come up with on a boring afternoon.
b - implies what is actually lacking in UFO claims: proof.
Would a very good scientific explanation of the UFO craft’s operating principles and mechanisms be enough to convince people that such craft can or do exist?
I'm willing to stipulate that aircraft made using technology 1000 years more advanced than ours could do many of the things that UFOs are claimed to do. And they would look weird as hell, too.