You would find it hard to justify your view of the modern battlefield by looking at the mix of equipment provided. The idea that a battleground can exist that is foot or armor only is mind boggling. Even Afghanistan has armor (in the form of aircraft more than tanks.)
In Iraq the armor (including APCs) provided mobility and ,for lack of a better term, do-it-yourself fortresses. The problem with that is the enormous support structure required to keep those forces supplied in the field. The modern battle tank is equivalent to WWII tank company and takes even more resources to support.
The antitank missiles these days, you are more likely thinking of RPGs and IEDs are more of a threat to the APCs and soft skinned vehicles. Which is where you see them being used. Those weapons have caused the development, again, of new vehicles to get troops in relative safely to and from combat. But unless your willing to pound every square foot of ground to a depth of 6 or 10 feet how do you make it safe for the troops?
If you can pound it, will the politicians accept the cost? The US lost Vietnam, it didn't loose it by the lack of dollars spent. The same goes for Korea and Somalia. It will probably be true for Iraq and Afghanistan.
There is IMHO no good solution. The politicians do what they want for the reasons they want and the rest of us have to dance to their tune.