Just a small point, some OT verses are quoted in the NT which would have had God's name in them, so although you are right that the name doesn't appear in the Greek text, its certainly not inppropriate to include YHWH in the OT quotes. The trouble is once WTS took this name on they can hardly take it back can they.
Also I had never considered the fact that Jesus was never recorded as saying God's name, although he does state something like 'I made your (His Father's) name known to them'.