Worst idea? No, it makes perfectly sense. I can't deal any damage in a fire magician with a fire bolt, but can with a storm of fire, because the fire robe absorbs in flat amount.
Armor absorbing in percentage is awful. Makes a sword and a warhammer wielded by a 2.5m tall orc equally effective vs a heavy plate armor. On FNV, a SMG outDPS a rifle with AP rounds vs unarmored targets but is useless vs heavily armored enemies and i love it. Percentage reduction homogenizes armor, progression, spells and weaponry.
That's all good for a turn based game, but in an action game, theoretically built around player skill rather than character skill, flat damage reduction sucks. Just look at Dragon's Dogma, or BotW, you are either so underequipped that mastery of the game's systems is irrilevant as you'll be stuck doing chip damage, or so overpowered that you are free to detach yourself completely from the combat as you'll melt anything anyway.
I don't want another Gothic 1/2 where your defensive options suck, enemies don't telegraph for shit, you can't reliably deal nor avoid damage and with random spurs of completely unneeded RNG. If you want to make an action RPG use the template of the actually good ones, that managed to make good player skill systems while also throwing a bone to the RPG players who want to see numbers go up and improve passively (because not every % reduction game is fucked up like Skyrim is), that released in the last 20 years like the Souls games or Nioh.
