I look at those hubs and those removers and simply think that's collectively poor design to have one of the most highly torqued tool used on a bike to have that little material at the key spot. And yes, a delicate balancing act between hardness and strength with the real answer being more material.
Both Park and Shimano make good tools. But designing (or not designing and simple following along and making) FWs and hubs that require that thin a tool - well we really need a new metal that is substantially stronger and brittle failure free than steel. Or live our lives dedicated to the notion that FW threads will always be properly greased and not sit for years and decades, then removed. Or just accept that every once in a while, those tools break. (A good reason to clamp them in a vise and turn the wheel with both hands vs using a big wrench. Much less exciting. You don't slam your hands into things.)