It would be one thing if anyone on the RNWT committee had any training in Biblical or Greek, or hell, any real (from a university) training in translation in general, and could justify their rewording.
But the RNWT is, as best as I can piece together, a bunch of guys reviewing Fred Franz's 75-80 year old notes from the original NWT, and then brainstorming what "sounds better" in modern English, with a preference toward phrasing that is "easy to translate".
So you end up with a translation based on notes from an older translation based on one guy's (maybe two guys if Gangas was involved) intermediate understanding of Biblical languages.