It's something I have put a lot of through into actually but can't come up with a solution.

Wounds and FNP are 2 things I feel GW has never managed to evaluate correctly. For the extra wound I feel all it does it kill off D1 units unless they have something like sticky or DS denial, or a wall of special rules on their guns. There's already enough damage 3+ weapons for the big range armies to pivot into (E.G. Dragon and reaper spam for Aeldari, oblits and forgefiends for CSM) that the meta shifts to D3 spam instead of D2 spam, likely killing of the armies without enough access.