Essentially, what's wrong (IMO, I don't claim any authority here) is that the current system is extensively playtested and works at least somewhat, and yours is a radical departure that at least at a cursory glance increases time spent on already excessive mission grind in an 'unfun' way (who likes to miss a lot? or even
be missed a lot?). Well, unless all you play is short vanilla campaigns or vanilla-ish mods, which I no longer have the stomach for.
But, in general, my opinion is that excessively low hit chances (something like sub-30% or so for most shots) do not make for interesting gameplay.
I tried my damnedest to tweak the JA2 nCtH to work for myself, and in the end it kinda worked
for me, but once I looked back at the vanilla JA2 accuracy model and asked myself "is this better?", it was not. Maybe it was not worse, but it was a lot of effort to stand still at best. Yeah, it was more 'realistic'. It was not more fun.
As to the current implementation, I'd need to do some more testing to speak with confidence (and I just lost my filters, again, so no X-Com until I restart my machine, which might take a little while
), but what I can definitely say is that:
1) Having a "model of low accuracy + tactics" means that modders lose some of their current control over accuracy. That is, while the game no longer outright lies and misleads, you now have to jump through extra hoops to match your vision and in-game reality.
1b)
Someone has to give the 'tactics' to the AI, tactics that are different from the vanilla model.
2) I don't mind caps as such. I mind
drastic caps like accuracy never going above 95% except for the rarest of circumstances, or not under 5%. I might be biased here, because I've grown to dislike d20 games a lot due to similar caps.
It fits well into a storytelling game where interesting events, good or bad, must not be too far apart. It's absolutely annoying in a simulationist wargame or tactics game.
1%/99% caps, sure, go ahead.
TLDR, I agree with Abyss that there should be a tweakable 'cover factor' for accuracy, at least. Maybe not for the player, but certainly for the modder to experiment with.
Auto-shots should only have the first shot use the accuracy-as-visible area model, and the the other shots should just scatter around the first shot in a cone or, better yet, rising/falling line. Ditto for shotgun pellets. And a horisontal line for auto-shot waypoint guns.
And, in general, I'd actually like it more if the cone was fixed, and thus accuracy was only ever a stat at a certain range (max range?, half max range?) and all other accuracies were actually calculated from that, using a fixed cone. Possibly with some extra input from all the dropoff values, but without them directly translating into accuracy percentages. This might not be what you're trying to accomplish here, though, and you certainly have no obligation to listen to me.