while I think it would be bad game design, I think it would be interesting to see mathematically how things would work if units had defensive abilities like "foes shooting at this unit re-roll 6s to hit" or something similar heh. of course GW would quite reasonably never go for something like that
That stands to make things too complicated, yeah.
I've already listed my wishlist for 40k, but to reiterate:
-> No more re-rolls (like, at all).
-> Improved cover (so it actually matters)
-> reduction in AP across the board. Like, absolutely no small arms have AP at all, mid-range guns (autocannons, plasma, etc.) get a -1, antitank weapons (lascannons, melta) get a -2. End of.
I *would* like to see/keep reactive stratagems a la Auspex Scan and Take Cover and so on, or reactive movement like Age of Sigmar's Reform order. Those we might actually see, maybe.
Shooting is just too Yhwh-condemneded powerful. It needs a colossal nerf, in my opinion, before the game can get interesting again. Right now it's very much the case that all your thinking happens before
the game is played. You show up with your army and then point-and-click and it's dull.