Title case in unavoidably mentally taxing. It's trivial to convert sentence case to title case, but highly non-trivial in general to convert title case to sentence case (I know, I write code to do this :-)) To do it right, context, or even general intelligence is required. Basically, converting to Title Case looses information (capitalization) that can be important.
Title case was invented when there were much limited typographical options than now, to emphasize, well, titles. On a web page, there are so many better ways to do it, there is no reason to preserve the archaic convention.
To my eye it does not even look that nice...
