First some brief background. I’ve always been somewhat fond of versions which render יהוה by Yahweh or something similar, partly because it makes better sense in many places to actually use a name when translating a name, partly because often using a title (i.e. “Lord”) interrupts the fluency of the text, and partly because, well, because I like to see little glimpses of Hebrew shining through into the translation.
Having said that, however, it is worth noting that there is a case for translating the name יהוה with the English “Lord.” The basis for the case is found in the NT, because whenever the NT quotes an OT text which includes God’s name it translates it as κυριος, ‘Lord’.
Now if that were all there was to it then I don’t think there’d be a strong case here. But wait, there’s more! The NT also consistently describes Jesus as κυριος, and so suddenly there is an important relationship established in the ambiguity of this designation for Jesus which the authors of the NT appear to self-consciously exploit.
A prime example is Matt 3:3’s use of Isa 40:3. First, here is what the MT for Isaiah says:
במדבר פנו דרך יהוה
ישרו בערבה מסלה לאלהינו
The LXX renders this thus:
ἐν τῇ ἐρήμῳ ἑτοιμάσατε τὴν ὁδὸν κυρίου
εὐθείας ποιεῖτε τὰς τρίβους τοῦ θεοῦ ἡμῶν
You can clearly see the transition from יהוה to κυριος which leads us to Matt 3:3
φωνὴ βοῶντος ἐν τῇ ἐρήμῳ·
ἑτοιμάσατε τὴν ὁδὸν κυρίου,
εὐθείας ποιεῖτε τὰς τρίβους αὐτοῦ.
So Isaiah makes clear reference to preparing the way for Yahweh to come. But what is in Matthew’s mind? Throughout his gospel Jesus is referred to as κυριος. So here we have some ambiguity—who are the preparations for? Are they for Jesus or for Yahweh himself? Reading on it becomes clear that John is anticipating the arrival of the Messiah.
The resolution to this apparent paradox lies, of course, in the divinity of Jesus, for the NT writers seem to apply both senses of κυριος to him.
So the danger in moving away from translating יהוה by ‘Lord’ in the NT is that the English reader loses this connection. As is inevitably the case when faced with such choices in translation, each choice has pros and cons and no choice will make everyone happy. Nonetheless, this particular translation choice has both biblical justification as well as theological significance, and so there is no a-priori case to dismiss the validity of the use of ‘Lord’ in English translations of the tetragrammaton.