Investing resources in rare item find chance is a two-edge sword. There are some very important minor soul shard for most playthroughs (soul attraction range, block chance, crit chance, re-roll chances, etc...). Sometimes, it's best to outright avoid rare item find chance to better ensure you get the runes you need.
"It'd be cool if" occasionally you found an item that let you split a regular soul into a single minor soul shard (maybe with a chance for more?). If a soul is sundered, it simply opens the soul shard choosing menu, with guaranteed 3 minor souls.
Bonus points if the soul shards you gathered explode from your body when you die and do some sort of animation. Kinda a reward for characters that gathered a lot of souls.