A smooth well machined jaw surface is important when working with expensive heat shrink terminals. This tool is designed to avoid molesting or damaging the heat shrink where a cheap or incorrect tool will damage it.
WARNING: No crimp tool for heat shrink terminals that I know of will reduce the occasional tear in heat shrink to 0%. You will occasionally tear a heat shrink terminal no matter what heat shrink tool you use. The proper tool for these terminals greatly minimizes the risk but does not entirely eliminate the risk and make it 0%.