I love music, and know very little about it. I have no education in the technicalities of the subject, and virtually no language with which to discuss it. But I do have strong opinions about what I like and don't, and have often been fascinated to find that people who are experts in the field can tell me, in some sense, 'why' I have those responses.
To take a Beatles example, since I was and always be a fan and most people know of their work (if you don't, check them out, they're great), I always hated 'Michelle' and loved 'Eleanor Rigby'. Never thought much about it, I just thought one was soppy and the other moving. Many years later, now many years ago, I read a musicologist's analysis of the two melodies, which explained, in detail too esoteric for me to recall, that 'Michelle' used a number of standard elements that made it virtually predictable, while 'Eleanor Rigby' was strikingly original. (I suspect that it is no coincidence that the lyrics are similarly trite and fresh, but that I leave as a mystery of the songwriter's art.) Lots of people like 'Michelle' and I don't mean to put them down; the damn tune sticks like glue, presumably because it fits so well into the patterns we expect - which makes it good pop and not much in the way of art.
The point is, I had no idea why I felt the way I did, and no language in which to address the problem. But the internal reactions were real, and should not be discounted just because I can't define a major chord or whatever.
Something similar happens with type all the time. I am not an expert on type; but I have worked with it, in many guises, for a quarter of a century and I do have some access to the language and even some of the theory of typography. Out of this, I gained what is called an 'educated eye', which really only means that I have greater sensitivity to my own subconscious reactions. (In this area.)
A simple and much-repeated experiment involves leading, the space between lines. Print out, at 600 dpi or better, a page of the same text, in the same typeface, at the same size, with about a four-and-half-inch paragraph width, and at various leadings, ranging from 10 on 10 to 10 on 20. Jumble up the pages, and ask any average person which one they would find easiest to read if it was a whole book. (There are different considerations for advertisements, or flyers, or even newspapers.) Then ask why. What normally happens is that people pick the 'correct' one (the rule of thumb gives 10 on 12 or 13 in most cases; it depends on the font and line width) and have the devil of a time articulating the difference.
Which doesn't mean they don't see it. But people seem to have a strange reluctance to admit the importance of things they are not consciously aware of. It's weird, after all these years of attempts at psychoanalysis - or maybe it's precisely because there is so much bullshit spouted about unconscious effects - but the entire history of desktop computing stands as evidence that people generally underestimate the importance of typographical appearance. But that's another rant.
You do not need expertise in typography to produce decent-looking web pages; you need talent. Failing talent, adherence to some well-worn rules will help immensely. Which is, of course, exactly what has happened with standard laser-printed hard-copy: Every major word-processing or DTP program has a set of defaults that produce generic but acceptable output.
Such, alas, is not yet true on the web. It will be soon, I expect and simultaneously, just as happened with DTP, high-end production will revert to the graphics professionals, many of whom will be the same people who have worked in old-fashioned typesetting and then DTP.
Meanwhile, just as in the 1980s half the country needed a crash course in page-layout and font usage (many of whom, incidentally, absorbed it without even realising what they were doing - which is fine, but curious), in the latter 1990s half the country, it seems, needs a different crash course in on-screen design.
But this one is more interesting, in a way, because it involves parameters that are new, as well as skills that are by now several hundred years old. A screen is not a piece of paper, and a scrollable text is not a print-out. That is why the questions involved are so intriguing.
But on screen or on paper, words are words, fonts are fonts, reading is reading, and typographers are the people who know about these issues. They deserve to be heard.