Re-specs are a good thing. The mythical "everything is good and viable" RPG doesn't exist. Often times it is just stabbing around in the dark as you learn the mechanics. A skill that in theory should be good could be complete trash and a skill that looks bad could be completely game-breaking.
You just ad a cost to re-specs in a single player RPG to discourage re-specing for every fight. However, it would allow players to respec when they realize what they picked cripples them.