Power fists were not ridiculous design, dummy, they were designed and implemented for Power Armor use, a person in Power Armor and with the left and right arm servos having a Power Fist installed was basically an unstoppable killing machine in close-quarters combat, rivaling that of the mighty Deathclaw. In fact, it makes more sense of it to be a military designed weapon than what Fallout 4 had in mind for it (A fucking construction tool?...really, Bethesda? When the sledgehammer or super sledge exist? Jesus christ), a sign that the Military most likely designed the Power Fist and Mega Power Fists as a counter-response to Deathclaws, just in case any of the pre-war beasts got out of hand and ended up killing everyone and everything, ally or foe. Makes a ton of sense, since Deathclaws have been known to be incredibly fast, deadly, and agile in rushing towards their prey, making ranged fire incredibly difficult to next-to impossible.
Also, I definitely prefer Fallout 1/2's design of the Power Fist and not 3, NV and especially F4's, as sounds incredibly powerful as an Unarmed weapon that emits a powerful energy blast upon contact as well as boosting the already formidable punching power of a Power-Armored user. Closest thing I can see something like in 'modern' fallout games would be the Unique Displacer Glove, Pushy in NV.