The development of the Alphabet (or indeed the Alef-Beit) is a fascinating one.
A number of books have appeared on the matter over the past decade, and they certainly make for fascinating reading... which brings me to the historical vs iconographic point.
Historically (or rather, to be precise, pre-historically), it seems more likely that the letters developed out of image-representations which over time became more abstracted and standardised (as happened also with Egyptian hieroglyphs, later demotic, and indeed further afield from our point of discussion with Chinese).
The story Huck brings is a wonderful imaginative reflection (and I realise he was not presenting it as historical, by the way, and take the point which sought to counter one way by which to read kwaw's earlier post).
Historically, however, it may be that the early development is even simpler. A representation is drawn, which, for the length of this post's sake, we'll just use one example of an Ox. Over time, only the horned head is represented, which eventually becomes an abstracted form to represent the sound of the word's beginning in that language. The stylised Ox moves further and further away from being recognised as ox-like, yet both the sound, and the letter's name, stick.
Over a thousand years later, someone may indeed draw on this oral tradition of letter meaning and incorporate its various qualities in imagery - whether these be letter-form similarity (e.g., Shin and 'three-prongedness'), meaning (e.g., Shin and tooth), or even more recently acquired numerical value - both ordinal and cardinal (e.g., Shin and 21st & 300).
The difficulty lies with some of the claims which have been made, and the assumed 'rectifications'. For example, investigating the imagery of the Major Arcana and the letters of the Hebrew alphabet (in conjunction with, for example, the Sefer Yetzirah) may quite wonderfully result in the reflections made by Wescott and incorporated by Mathers in what has become Golden Dawn generated views. This does not mean that Shin and XX Judgement have intrinsic connections, but rather that one can see how they decided to make such, and that any deck which accepts their peculiar views will incorporate this element, even if without conscious awareness, into the deck's depictions.
There is absolutely no doubt that the RWCS, BOTA, CH Thoth, and a host of others have incorporated this particular letter association into their respective decks.
Similarly, there is no doubt that many other decks have incorporated other associations. The differences do give such differences in tonal qualities to the decks that, for the aspiring esotericist, it brings to the fore important bearing, for prolonged usage of one type over another will undoubtedly impact on the ways in which the cards are entered and unveiled.
For the historical reportage, it makes not as much difference, for there it is a matter of carefully presenting what various people have done, and plausible explanations as to why.
It seems, then, that embedded in the nature of this thread is not only the various reflections brought here by those of us who continue to post, but also as to (to return to one of the very early questions) why it may be of interest.
In a nutshell, and apart from the historical interest, it may be of interest as these Hebrew letter associations are very likely to have had an impact and influence on most decks we are likely to obtain... or even design!