You are right, there has been some discussion about that already. Unfortunately it is not easy to change the way the shield is held by modding alone. There have been some attempts at it already, but the main problem is that the game sees the shield centered at a certain part of the arm, no matter where the visible shield ends up.
So if we change the shield alone it will look different, but arrows for example will pass through it or get stuck at places that are not even covered by the visible shield, so thats not a solution. In some mods the position has been changed anyway, but mostly it leads to the faulty hitbox. Only most mods don't suffer from these side effects as badly as we would, because in Vikingr the shield skill is set to 0, so that no arrows get blocked that don't hit the shields hitbox.
In native the phenomenon of higher shield skill is often called "forcefield", since arrows get caught in the shield that didn't even hit it originally, so some mis-position can be covered up by that in other mods. But without this forcefields any inconsistencies get obvious.
Yet another problem is that kite shields would be held yet differently, with the long fist extended towards the tip and the upper arm fixed to the round end, and holding these in the round-shield style would probably look even worse than it does right now.