This is Pripyat today:
Not so barren compared to what Fallout 1/2 show.
On the other hand the radiation forgeted up the DNA of local Fauna. Pretty everything born after the incident is mutant.
We don't need to spend our time funding the military so much anyway. I for one, am glad that the president decided that the military should be shrunk down to what it was before WWII. We spend over $600 Billion (USD) annually buying and making weapons and armor that we will probably never use.
Most of these funds have been spent trying to clean up previously-invaded nations that we have spent tireless amounts of time and effort to fix, but most of this money is actually getting wasted. When we currently left Afghanistan, most of our armored vehicles were sent to scrap yards to be junked for extra parts. Some of these parts got in the hands of the Taliban as well. This itself is an absolute waste of tax payer money.
It's just not necessary in this time period. Plus we also have military bases stationed in almost every nation on Earth and these also take sufficient funds to stay operational. This money could be used for more domestic purposes like financing more federal student aide programs and stuff that can actually stimulate our economy and help our own people instead of some foreigners in a distant land who will grow to hate us.
Armored Vehicles:
This is what we left behind. These things are too big and heavy for a conventional fight. They had limited uses.
Weapon Development:
The only reason why we continue to make weapons is because every else continues to develop them.
Bases: Abandoning most if not all of our oversees bases would require that NATO either step up their defense funding and increase their military size. Countries that we occupy would have to fend for themselves.
Having all those over sees bases also allows us to project our navy any where in the world. Abandoning them could weaken our sphere of influence.
Harm: you speak like drone technology won't improve at all. Seriously, it's not going to be flawless yet. but if its allowed to grow, all the issues you've stated can be fixed. Not to mentioned that most military aircraft, drone or manned, have anti-missile defenses themselves.
Drones probably won't be as numerous and be kept around for low intensity conflicts. However they won't be without flaw:
Electronics aren't cheap and are made out depleting none renewable resources. At least with humans around, wreckage can be salvaged and recycled.
Humans can think for themselves and adapt to the battlefield, even if communications are cut off. Drones can be jammed, hacked, or emp'd, they need a master command them.
Missiles:
Depends on what you are referring to.
There are several types of SAMS ranging from Radar guided missiles, Infrared Missiles, and electro optical missiles.
Infrared Missiles lock onto a heat source, they are prone to being fooled by flares.
Radar missiles use battlefield Radar systems to lock onto targets, they are immune to flares. Radar can be jammed, however newer systems are always being built. Some are harder to jam than others. Anti-Radiation missiles can take out radar equipment, but the aircraft carrying them are vulnerable to Infared and Electro Optical missiles.
Electro Optical Missiles rely on cameras and images to lock on to targets. They can be affected by line of sight.
