I agree that a "Str & Dex" martial character is generally a bit sub-par compared with a straight-up "Str OR Dex" build - which is a shame because well rounded physical prowess is a bit of a hallmark of many fantasy heroes. However as others have pointed out, a universal rule like the one porposed would crash into a lot of other things in the game like monster attacks, AC, etc. It would be hard to untangle.
Perhaps a few opt-in modular components that can be taken as part of the "Str & Dex" build might help - a fighting style and a feat? A few subclasses with attractive features that rely both abilities, such as Enforcer rogue, Slayer barbarian, Mighty-Grip monk, or Myrmidon fighter?
This way, if you invest ASIs and resources into your Str/Dex build, you can keep up with those who invest their ASIs and resources in pure-dex and pure-str builds? The tricky part would be striking the right balance - the feats, styles, and subclasses would need to appear a bit OP on paper but a lot of that perceived power would be compensating for the MAD build. It would be hard to judge.
D.
Perhaps a few opt-in modular components that can be taken as part of the "Str & Dex" build might help - a fighting style and a feat? A few subclasses with attractive features that rely both abilities, such as Enforcer rogue, Slayer barbarian, Mighty-Grip monk, or Myrmidon fighter?
This way, if you invest ASIs and resources into your Str/Dex build, you can keep up with those who invest their ASIs and resources in pure-dex and pure-str builds? The tricky part would be striking the right balance - the feats, styles, and subclasses would need to appear a bit OP on paper but a lot of that perceived power would be compensating for the MAD build. It would be hard to judge.
D.