Opinion | At Last, F-16 Jets for Ukraine

We don't have a long enough memory. Remember that we lost 3374 fixed wing aircraft during Vietnam to anti-aircraft missiles and guns that were supplied by the predecessors of the current Russian Federation, and we were doing some pretty serious SAM suppression and anti radiation missions to reduce that rate. Ukraine doesn't have that kind of stuff, nor the trained personnel even if we supplied it.
At some point, sending the Ukrainians more weaponry is simply killing more Ukrainians.

Still won't have the legs to hit far into Russia, if that's part of the plan, but dissimilar aircraft will help prevent friendly fire incidents.