I appreciate what you're saying, but IMHO almost none of the samples on that page looks sufficiently professional that I would use it to set a textbook. Computer Modern has at least stood the test of time, and gives a clean, uniform appearance to text and mathematical type.
If I were setting a serious work, I would like to use a high quality serif font, something like Emigre's Mrs Eaves or Adobe's Arno Pro, but alas, these fonts have a rather limited range of mathematical glyphs, which means you either get the "two similar but different fonts" problem (which nearly always looks bad) or you have to pick a font that isn't as nice for the body text just because it has matching math symbols available.
Should have mentioned to jump to the bottom of the page. Many of the examples are ugly, but Minion and Utopia are, of course, pro Adobe fonts used in a large number of professionally-typeset books.
If I were setting a serious work, I would like to use a high quality serif font, something like Emigre's Mrs Eaves or Adobe's Arno Pro, but alas, these fonts have a rather limited range of mathematical glyphs, which means you either get the "two similar but different fonts" problem (which nearly always looks bad) or you have to pick a font that isn't as nice for the body text just because it has matching math symbols available.