I'd attribute it to the generally immature writing style used by the WT. As I've noted before (in the posts about agentless passives--"It has been said"), the WT writers use many stylistic devices common to inexperienced writers who want to sound more authoritative. The use of the third person is assumed by many inexperienced or naive writers to convey a certain weightiness to their words. These writers tend to think that anything personal is less authoritative and therefore less credible, so they'll often go to great lengths to avoid using the first person.
Just another example of why the WT Writing Department would probably flunk my freshman composition class.
Of course, they could also be writing in this fashion to sound more "God-like." I'm sure Jah would always refer to the JWs in the third person!
Jankyn, self-proclaimed grammar dork