There have been a few posts with suggestions to make all stats useful for all classes. The issue with making all stats equally useful remains that people only get X points per level, and encouraging everyone to spread their stats around just produces a party in which everyone has pretty much same stats as every other member despite having different weapons and attack styles.
I have seen games where STR is the only stat for increasing the damage of basic attacks, but those games are typically JRPG's where you don't allocate your stats, they all increase when you level up, and they also have a separate Magic attack stat which governs how powerful your magic attacks are, to differentiate physical attackers from casters.
Your suggested system will produce much more homogeneous characters than the current system.
(Also, this game seems designed around the idea that you have a max of 6 AP and get 4 AP per turn, and you cannot permanently increase either of those numbers.)
