Dexterity is primarily useful for the heightened reflexes bonuses and MINOR armor requirements(Unless your´s a ranger type of character then it will be a MAJOR armor requirement)If you don´t like doing critical hits that kill most of your foes with just one strike and dodging melee blows making your enemy a fool don´t bother to spend points in dexterety just for armor requirements...
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Sorry for bad english i am brazilian and that is just my point of view...I hope it helps XD