dave2008
Legend
The proposed house rule cannot make your bonus to hit go down. The OP suggested prof + str + dex (with max +5).Not a fan.
A base goblin has 8 str 14 dex. Normalling this is +4 with its weapon. With that houserule it is +3.
Kobolds go from+4 to +2
And poor animals.
That's a housrule that you would need to change AC calculations as well to fix. It's a lot of work.
EDIT: Nevermind, I was missing the -1 on str, I see your point now. Maybe it only add's positive modifiers.