The way heroes equipment is handled is giving me headaches

I like to switch between my characters often to play different classes and styles. Because I came back to the game recently and am poor, I only have enough equipment for one "team" of heroes, so I have to transfer weapons, recycle runes etc.. from one characters' heroes to another, which is time consuming. Tonight during a brain fog moment I applied a minor fast-casting rune onto a sup vigor armor piece (I forgot I had already applied it).

Is there a non-technical reason why we can't share equipment and armors for heroes between characters? Or at least for mercenary heroes?