Well thank you, my friend. :) That's a very nice compliment.
But the relevance is that maybe our modern "lens" is provided by our sitz im leben. For more than half of the time since the Resurrection the Bible just wasn't available, in practical terms outside of the living community. Not only was gentile Europe shockingly (when compared to our Jewish older brothers) illiterate, but even had they been able to read, there weren't that many Bibles to go around.
That's interesting. In fact, just off the top of my google (umm ....., I mean head) I remember that sitz im leben has to do with time and place perspective, including personal perspective. Since I have certainly used this idea to defend Biblical interpretations I freely and fully acknowledge that it is proper to use old world context to interpret scripture. When I first read selected books from the Bible I had zero information about such context.
I suppose the trick is to try to define the universality or timelessness of any given verse IN ITS PLAIN MEANING. I'll bet that definition for many verses has changed multiple times through the ages. However, I like to think that for the very core of teachings on Christ specifically, and God generally, that the exact same meaning has survived all these years, without need of any time or cultural consideration. I think we all have to have faith that the message of Christ, and His mission, are timeless without need of extravagant interpretation by ANY side. Since you and I are both Christians, we are examples.
Of course you are right that only relatively recently has a Bible been reasonably available to (many of) the masses. We Sola Scriptura (ists?) would say that correct oral teaching still "counted" as Sola Scriptura to the extent of its faithfulness to scripture. We obviously think there was "some" error in there over the first several centuries. However, all the points of belief that make one Christian, and more, did survive and flourish in all "truly" Christian faiths.
I wouldn't be at all surprised to learn someday that some things I think are true are dead wrong because of sitz im leben, so I think you raise an excellent point. I would probably most expect to find that in the area of eschatology. :)
Of course, Your mileage varies, but an image I'm trying to suggest ... from a nutritional POV partaking only of Scripture is a newfangled and unbalanced diet, and not what Christians ate for centuries. So one might conjecture that an unbalanced diet (Sola Scriptura) would lead to an unbalanced opinion (ditto). I don't mean this as some kind of triumphant "Aha!" but just to depict/adumbrate another POV.
Adumbrate? Well, just off the top of my Free Online Dictionary (umm ....., I mean head) I remember that you are proffering a supportable and reasonable view without demanding anyone's acceptance of it as fact. (Man, you've got a good vocabulary. :) Anyway, I would respectfully disagree that partaking only of Scripture is an unbalanced diet. In the nutritional comparison, our bodies NEED nutrients from different food groups to be healthy. The supposition appears to be that we NEED Tradition in order to be healthy, i.e., that the Bible is not enough for the Christian. If true, then for spiritual health, what would you say is lacking in the Bible?
TRIAL BALLON ALERT: I reserve the right to say "An enemy wrote this while I was asleep." I am just trying to figure this out here.
The non-confrontative answer to your closing question is, I think, that we all know that WE reading the Bible need a context of God-given Faith and of prayer. We need the ecclesia to have preserved and handed down the Scriptures to us. And whether or not we, strictly speaking, "need" them, we certainly profit from the scholars and their tools, dictionaries, concordances, etc.
I remember the Bible came alive for me when I was reading Genesis and came to the Terebinths of Mamre and SAW Abraham and his courtesy. That seeing was the gift of God.
Oh, man ... It's a good question, the "what is lacking". I have no clue how to answer it. Let me take a stab:
If you read some hymns without the music, you think, Wow, what tawdry poetry! But WITH the music, sung in Church, it can be a great hymn both objectivley and in terms of how it prompts one to look to God in Love. Check out this hymn which just totally blew me away at Mass this weekend. Being a very manly man, as I'm sure you've observed, I am rarely overcome with tears in Church, since I don't feel pain, I inflict it. Yeah, right. So I'm in my wheelie-chair saying to myself, this is absurd! IT's a HYMN! You can sing it!, Trying, and crying.
I think tradition and the Church is like the music. You all have good concerns about idolatry and a diversion of attention away from GOd. But (it's like) I can't hear you because I am dancing before the Lord. And If I dance away it is as if to gesture at a flower as if to say, "Look at this wonderful thing" and then dance back to Him and say, "And YOU made it from your wonder which surpasses that of the flower more than diamonds surpass mud!"
So while part of the fuel of our feelings when people diss our Lady is, "Uh, That's my mother you're taking about, watch your mouth!" Another part is frustration that because we dance to the flower, our friends rebuked us for dancing away from the Lord.
And if I were to say what the Bible lacked in a set of doctrinal propositions, I think it would be to miss the point. It is not disrespect to rhythm to say it lacks melody and no disrespect to melody to point out its rhythm (or lack thereof). I think likewise the Church needs the Bible, clearly. But the Bible needs the Church.