The practice of capitalizing titles presents issues particularly when the titles are transported into new contexts, for example via an RSS feed or search engine harvest. ALL CAPS MIGHT LOOK OK AS A <TITLE> ON YOUR WEB PAGE, but a search engine might hesitate to scream at people.
This is not by any means a new problem, but it's one that changes from era to era because of the symbiotic relationship between language and printing technology. Here's what Charles Coffin Jewett wrote in 1853 when discussing how libraries should record book titles:
The use of both upper-case and lower-case letters
in a title-page, is for the most part a matter of the printer's taste,
and does not generally indicate the author's purpose. To copy them in a
catalogue with literal exactness would be exceedingly difficult, and of
no practical benefit. In those parts of the title-page which are
printed wholly in capitals, initials are undistinguished. It would be
unsightly and undesirable to distinguish the initials where the
printer had done so, and omit them where he had used a form of letter
which prohibited his distinguishing them. It would teach nothing to
copy from the book the initial capitals in one part of the title, and
allow the cataloguer to supply them in other parts.
In German and other languages, nouns are capitalized; this used to be true of English (take a look at the US Constitution). In German, it's easy to tell nouns from verbs, which might be very useful if we still had it in English. Still, I enjoy being able to write that something is A Good Thing. It gives me a way to intone my text with an extra bit of information.
The rules for how English should be capitalized have become quite complicated. Here and here are two web pages I found devoted to collecting capitalization rules. Some of them are pretty arcane.
simplify spelling, grammar and capitalization, led by people like Melvil Dewey. I'm guessing part of the reason was the annoyance of needing to press a shift key on those newfangled typewriters. But spelling and capitalization reform didn't get very far. Perhaps they tried to publish articles and got stopped in their tracks by a unified front of copy editors.
If anything, the current trend is in the direction of making capitalization even more idiosyncratic. In addition to a proliferation of Product names like iPod and eBay that have crossed over into the language mainstream, the shift from print to electronic distribution of text does a better job of preserving the capitalization chosen by the author, thus allowing it to better transmit additional meaning.
The ability to increase the information density in text is useful in a wide range of situations, for example, when you have only 140 characters to work with, or when you want a meaningful function name, like toUpperCase(). If your family name is McDonald, you probably have strong feelings on the issue.
My guess is that life will become increasingly case sensitive. You may already be aware that it takes 8 seconds, not one, to transmit a 1 GB file over a 1 Gb/s link. And that SI unit Mg is a billion times the mass of a mg. If you are a Java programmer, If you know the difference between an integer and an Integer, you'll quickly learn about NullPointerExceptions.
Did you know that there are a small number of characters that are different in "upper case" than in title case? They are: Letter DZ, LETTER DZ WITH CARON, LETTER LJ, LETTER NJ, and LETTER DZ. The lower case versions are ǳ, ǆ, ǉ, and ǌ; the upper case versions are Ǳ, Ǆ, Ǉ, Ǌ, and the title case versions are ǲ, ǅ, ǈ, and ǋﬁ, ﬂ, ﬃ, ﬄ, ﬅ, ﬆ. And don't forget your Armenian ligatures, ﬓ, ﬔ, ﬕ, ﬖ, ﬗ. For this reason, being "case insensitive" is poorly defined- two strings that are equal when you've changed both to uppercase are not necessarily equal after you've changed them to lower case!
So what do I do when I write about ebooks I don't use a dash? When the word appears in a title, I capitalize the "B". I can't wait till they translate this rule into Armenian.