It is amazing that Congress can deny us the wall. This has shown me a lot about our country and its government. I think "deep state" is really "open state" now, there is no attempt to even disguise the arrogance of them doing contrary to what their constituents sent them to do.
Remember "kill Obamacare"? Same kind of thing.
Regarding the wall height:
The height is certainly the result of an engineering analysis. One criteria might very well be and likely is, how high can the wall be to insure that some falling from that height is not fatally injured? That is, build the wall high enough so that someone falling from a ladder of that height might be injured but not killed.
As a designer, the wall presents many interesting design problems not normally encountered
The result is not a “killer wall”