No, PG defense is easily one of the most overrated skills of their game. Practically none of the elite point guards are elite defenders nor were projected to play elite defense. As long as you dont draft a guy who doesnt put in any effort on defense you're fine.
And no it isnt valuable if they can guard bigger players because no bigs really punish mismatches anymore. If anything its valuable if your big can guard smaller players because you got guys like steph, kyrie and dame breaking down big guys all night. There isnt any bigs punishing smalls on a consistent basis. The game has moved away from that.