All that is very well on paper but your solution has few unintended conseqences.
1. Nerfing fire chance is simple enough but increasing HE damage will not make that much difference on BB. And that's because HE still needs to penetrate to do damage. Out of five sections of the ships that you can damage (bow, fore midship, aft midship, stern, superstructure) BBs have enough armour on 2 of them (midships) to deny any direct HE damage. Aiming at bow or stern is unreliable with cruiser accuracy and not every DD has enough pen to do damage. Which leaves superstructure but tha means there is a limit of damage you can do that way. On the other hand the ones that would suffer for this change would DDs. Since they have on armour to speak of HE wiould always pen and do more damage.
Solution to that could be system with HE from WOT. If you pen you do standard 33% damage, if you don't you do some damage proportional to the thickness of armour in that spot. That would mean you would be more reliable when dealing damage but it wouldn't be much different from being set on fire, you'd be constantly loosing minor amounts of HP until you're whitled down to nothing - just as annoying.
2. Buffing AP penetration wouldn't be much of a problem but to what extent? Until you can pen belt armour? At what angle? At what distance? Besides then BB players would start complaining (and not without reason) that they cannot tank properly. Cruisers can pen bow and aft sections but aiming at them at long ranges is once again unraliable. And getting close to BB is asking to be deleted.
Overpens are even more of a trouble. The only way to limit them (as I can see at least) is to limit time fuse on the AP rounds. But that once again would hurt not only BBs, but all ships as we would see increase in damage dealt by cruisers. Especially DDs would suffer as they would see increase in damage dealt to them from 10% to 33%. And manipulating with mechanics this way it would be easy to confuse players: "So the fuses on CA/CL are different then on BB and DD? And RN cruisers have yet different ones?" - that's one way road to overly complicate mechanics.
Your complaints about ships in the game not following historical roles are also odd. Of course in the game historical roles will not be followed. Who would want to play DDs if their role would be to cruise up and down the line and spot for rest of the team? Not to mention what sesnsible carrier captain would sail within 20km from the enemy fleet. Because it's a game every ships in it needs to have at least a chance to defeat any other ships it meets in the field. Regardless whether that's how it was in history.
