Top-heavy Humvees cause problems.

As this site on vehicle accidents shows armoring the Humvees wasn’t all peaches and cream. It also illustrates why the military design and development process is so long, complex and expensive.

Had the armoring been done in the standard way, test models would have been build, handling characteristics determined and a training course and manuals for the operation of the altered vehicles would have been developed. All that, of course, in addition to testing for the effectiveness of the armor in doing what it was supposed to do.