well lets look at parry from 2.0. it synergized with dexterity and strength in a way that made it...less dull. But being a random stat that is unpredictible, it just simply wasnt something you invested in. It was more interesting though, to say x strength made it block more % incoming damage and x dexterity made it proc more often, so Id say it was somewhat of an interesting(yet unreliable) stat. In all honesty I really do not know what kind of secondary would be more interesting and stats are only more interesting if theres a rarity or limit or where stacking two stats gives a better effect than just dumping everything into one. literally could shove str, int,dex into DAMAGE. and nothing would change for DPS at all. tanks sure, but not even healers.