I think it's a little more complicated than that: RPGs tend to reward tactical but not strategic optimization. Local cleverness and tradeoff management is always useful and often necessary, but past the immediate future (a specific battle, or at most a unit of time convenient for inventory management) strategy becomes dominated by idealism in scripted decisions (if a choice is given at all) and exploration of the game's unscripted components.

Its roots seem partly accidental and partly didactic, but in practice I wouldn't be surprised to find that this reward system caters to a certain cognitive style. In terms of Bartle type, at any rate, it's straightforwardly going to attract exploratory/acquisitional players (spades or diamonds); Bartle was working with fairly restricted gameplay possibilities, though, so his typology might easily miss some important options. Perhaps conventional game design has missed a demographic it might exploit by encouraging more strategic thinkers?