User blog comment:Silver-Haired Seireitou/Sake Time with Sei - Can Arrancar Use Kidō?/@comment-30807545-20140413170104/@comment-2089817-20140413172253

Except that the Hollowfication Virus wasn't created by the Hōgyoku, nor did Aizen ever use it on the Visoreds whatsoever. Urahara used the Hōgyoku to stabilize the Visoreds' conditions, turning them into the hybrids we've seen. Aizen used the Hōgyoku solely to accelerate and "force" the growth of a Hollow into an Arrancar, which arguably stunted their growth, but that's a discussion for another time.

Besides, bringing in the Hōgyoku is moot, since this discussion is about whether or not Arrancar have the potential to use Kidō or not; not if there is some kind of magical method to grant them that ability.