well, having the 500dmg rune not deal 500 dmg all the time, but deal dmg dynamically, based on resistance/weakness would change that.
also having a more reasonable focus gain would change that. so rather than filling up 20% of your total max focus with each hit, converting 20% of the dmg dealt into focus, would reduce focus gain, and therefor prevent spamming.
also having more options with crafting and enchantment, might just be enough to encourage using other weapons with different movesets, rather than your 500dmg rune.
and improving stealth builds making them as rewarding as spamming a rune would give another option that is more moveset based.
so yeah, i think these points would change that.
also, on another note, i noticed some other posts similar to your OP. if you could maybe take a look at them as well? so if they fit our discussion here, i could merge them together for more awareness. having everything in one place might help push the topic.