This are good ideas. I think however we won't be able to do much unless the player is able to lose limbs.
We need enemies with special limb cutting abilities and the ability for limbs to be gored after certain number of damage.
The regrowth, bionic limbs, etc would be really awesome.
You could even leave a "arm/leg" item on the ground that, with a specific mutation could be just reattached. Or eaten, if you are desperate. If not, another mutation could grow one back if you eat enough. Or you use a CBM that's just an arm (after all, with the growth of cbms in the market, I'm pretty sure bionic limbs -better than the ones we have today- would be a thing), or there could be stronger bionic arms, and etc.
If it were for me I'd go like the I.V.A.N. system of limbs but a bit further: maybe you could just gain or install as many arms as you want, with a limit of course, and it would give severe buffs to melee and any hand activity but severely increasing encumbrance unless you craft specific clothes.
As long as you have more arms than two, you can wield most stuff.
OK, I might have gone overboard but it was nice to just throw ideas.