There will always be an "optimal" strategy, in every kind of game you play. Devs are humans, and even through all the balancing, there will always be in every game the most cost-efficient way of spending points, even by a 1%. If you always go for the optimal strategy only, of course you'll have problems finding variety
Often a big part of the fun will be finding ways of playing a game which aren't the most efficient or perfect ones, but make you enjoy and still are somewhat competitive.
