Quantity has a quality all its' own. A swarm of a thousand quadcopters negates any drawbacks you've mentioned, and would be cheaper than even a single Bayraktar or Reaper (not even including their 6 figure weapons payload). And we're already seeing drone carrying "motherships" that drop multiple quads and have RF repeaters to extend range to 50km+.

It's a lot like the switch from battleships to aircraft carriers in the early 20th century. When a single squadron of cloth and wooden biplanes became capable of sinking a 50,000 ton armored warship that took 5 years to build, the writing was on the wall, and the countries who didn't adapt lost.